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February 17, 2010

Technical Interview Questions (Part 1/3) [Networking] Edited & Maintained by SYED JAHANZAIB / aacable@hotmail.com

Filed under: General IT Related — Syed Jahanzaib / Pinochio~:) @ 6:33 AM

Technical Interview Questions (Part 1/3)
[Networking]


Edited & Maintained by SYED JAHANZAIB / aacable@hotmail.com


1.    What is an IP address?

2.    What is a subnet mask?

3.    What is ARP?

4.    What is ARP Cache Poisoning?

5.    What is the ANDing process?

6.    What is a default gateway? What happens if I don’t have one?

7.   Can a workstation computer be configured to browse the Internet and
yet NOT have a default gateway?


8.    What is a subnet?

9.    What is APIPA?

10.   What is an RFC? Name a few if possible (not  necessarily
the numbers, just the ideas behind them)

11.   What is RFC 1918?

12.   What is CIDR?

13.  You have the following Network ID: 192.115.103.64/27.
What is the IP range for your network?


14.  You have the following Network ID: 131.112.0.0. You need at least
500 hosts per network. How many networks can you create? What subnet
mask will you use?


15.  You need to view at network traffic. What will you use? Name a few
tools


16.   How do I know the path that a packet takes to the destination?

17.   What does the ping 192.168.0.1 -l 1000 -n 100 command do?

18.   What is DHCP? What are the benefits and drawbacks of using it?

19.   Describe the steps taken by the client and DHCP server in order to
obtain an IP address.


20.   What is the DHCPNACK and when do I get one? Name 2 scenarios.

21.   What ports are used by DHCP and the DHCP clients?

22.   Describe the process of installing a DHCP server in an AD
infrastructure.


23.   What is DHCPINFORM?

24.   Describe the integration between DHCP and DNS.

25.   What options in DHCP do you regularly use for an MS Network?

26.   What are User Classes and Vendor Classes in DHCP?

27.   How do I configure a client machine to use a specific User Class?

28.   What is the BOOTP protocol used for, where might you find it in
windows network infrastructure?


29.   DNS zones – describe the differences between the 4 types.

30.   DNS record types – describe the most important ones.

31.   Describe the process of working with an external domain name

32.   Describe the importance of DNS to AD.

33.  Describe a few methods of finding an MX record for a remote domain
on the Internet.


34.   What does “Disable Recursion” in DNS mean?

35.   What could cause the Forwarders and Root Hints to be grayed out?

36.   What is a “Single Label domain name” and what sort of issues can it
cause?


37.   What is the “in-addr.arpa” zone used for?

38.   What are the requirements from DNS to support AD?

39.   How do you manually create SRV records in DNS?

40.   Name 3 benefits of using AD-integrated zones.

41.   What are the benefits of using Windows 2003 DNS when using AD-
integrated zones?


42.  You installed a new AD domain and the new (and first) DC has not
registered its SRV records in DNS. Name a few possible causes.


43.   What are the benefits and scenarios of using Stub zones?

44.   What are the benefits and scenarios of using Conditional Forwarding?

45.  What are the differences between Windows Clustering, Network Load
Balancing and Round Robin, and scenarios for each use?


46.   How do I work with the Host name cache on a client computer?

47.   How do I clear the DNS cache on the DNS server?

48.   What is the 224.0.1.24 address used for?

49.   What is WINS and when do we use it?

50.   Can you have a Microsoft-based network without any WINS server on
it? What are the “considerations” regarding not using WINS?


51.   Describe the differences between WINS push and pull replications.

52.  What is the difference between tombstoning a WINS record and simply
deleting it?


53.   Name the NetBIOS names you might expect from a Windows 2003 DC that
is registered in WINS.


54.   Describe the role of the routing table on a host and on a router.

55.   What are routing protocols? Why do we need them? Name a few.

56.   What are router interfaces? What types can they be?

57.   In Windows 2003 routing, what are the interface filters?

58.   What is NAT?

59.   What is the real difference between NAT and PAT?

60.   How do you configure NAT on Windows 2003?

61.   How do you allow inbound traffic for specific hosts on Windows 2003
NAT?


62.   What is VPN? What types of VPN does Windows 2000 and beyond work
with natively?


63.   What is IAS? In what scenarios do we use it?

64.   What’s the difference between Mixed mode and Native mode in AD when
dealing with RRAS?


65.   What is the “RAS and IAS” group in AD?

66.   What are Conditions and Profile in RRAS Policies?

67.   What types or authentication can a Windows 2003 based RRAS work
with?

68.   How does SSL work?

69.   How does IPSec work?

70.   How do I deploy IPSec for a large number of computers?

71.   What types of authentication can IPSec use?

72.   What is PFS (Perfect Forward Secrecy) in IPSec?

73.   How do I monitor IPSec?

74.   Looking at IPSec-encrypted traffic with a sniffer. What packet types
do I see?


75.   What can you do with NETSH?

76.   How do I look at the open ports on my machine?









“ANSWERS”

1) What is an IP address?

An Internet Protocol (IP) address is a numerical label that is assigned to devices participating in a computer network utilizing the Internet

an IP address is a 32-bit number thatidentifies each sender or receiver of information that is sent in packets across the lan/Internet.

An IP address has two parts: the identifier of a particular network on the Internet and an identifier of the particular device (which can be a server or a workstation) within that network. On the Internet itself – that is, between the router that move packets from one point to another along the route – only the network part of the address is looked at.

2) What is a subnet mask?

A subnet mask allows you to identify which part of an IP address is reserved for the network, and which part is available for host use. If you look at the IP address  alone, especially now with classless inter-domain routing, you can’t tell which part of the address is which. Adding the subnet mask, or netmask, gives you all the information you need to calculate network and host portions of the address with ease. In summary, knowing the subnet mask can allow you to easily calculate whether IP addresses are on.
Subnetting enables the network administrator to further divide the host part of the address into two or more subnets.




3) What is ARP?

Short for Address Resolution Protocol, a network layer protocol used to convert an IP address into a physical address (called a DLC address), such as an Ethernet address. A host wishing to obtain a physical address broadcasts an ARP request onto the TCP/IP network. The host on the network that has the IP address in the request then replies with its physical hardware address.


ARP is a very important part of IP networking. ARP is used  to connect OSI Layer 3 (Network) to OSI Layer 2 (Data- Link). For most of us, that means that ARP is used to link our IP addressing to our Ethernet addressing (MAC Addressing). For you to communicate with any device on your network, you must have the Ethernet MAC address for that device. If the device is not on your LAN, you go through your default gateway (your router). In this case, your router will be the destination MAC address that your PC will communicate with.



4) What is ARP Cache Poisoning?
a method of attacking an Ethernet LAN by updating the target computer’s ARP cache with both a forged ARP request and reply packets in an effort to change the Layer 2 Ethernet MAC address (i.e., the address of the network card) to one that the attacker can monitor. Because the ARP replies have been forged, the target computer sends frames that were meant for the original destination to the attacker’s computer first so the frames can be read. A successful APR attempt is invisible to the user.
ARP cache poisoning, also known as ARP spoofing, is the process of falsifying the source Media Access Control (MAC) addresses of packets being sent on an Ethernet network. It is a MAC layer attack that can only be carried out when an attacker is connected to the same local network as the target machines, limiting its effectiveness only to networks connected with switches, hubs, and bridges; not routers.


5) What is the ANDing process?

In order to determine whether a destination host is local or remote, a computer will perform a simple mathematical computation referred to as an AND operation. While the sending host does this operation internally, understanding what takes place is the key to understanding how an IP-based system knows whether to send packets directly to a host or to a router.

Notice that when the resulting AND values are converted back to binary, it becomes clear that the two hosts are on different networks. Computer A is on subnet 192.168.56.0, while the destination host is on subnet 192.168.64.0, which
means that Computer A will next be sending the data to a router. Without ANDing, determining local and remote hosts can be difficult. Once you’re very familiar with subnetting and calculating ranges of addresses, recognizing local and remote hosts will become much more intuitive. Whenever you’re in doubt as to whether hosts are local or remote, use the ANDing process. You should also notice that the ANDing process always produces the subnet ID of a given host.

6) What is a default gateway? What happens if I don’t have one?

A default gateway is used by a host when an IP packet’s destination address belongs to someplace outside the local subnet. The default gateway address is usually an interface belonging to the LAN‘s border router.
In computer networking, a default network gateway is the device that passes traffic from the local subnet to devices

on other subnets. The default gateway often connects a local network to the Internet, although internal gateways for connecting two local networks also exist.


7) Can a workstation computer be configured to browse the Internet and yet NOT have a default gateway?

If we are using public ip address, we can browse the internet. If it is having an intranet address a gateway is needed as a router or firewall to communicate with internet.

8) What is a subnet?

A portion of a network which shares a network address in which each component is identified by a subnet number.
A subnet is a logical organization of network address ranges used to separate hosts and network devices from each other to serve a design purpose.

In many cases, subnets are created to serve as physical or geographical separations similar to those found between rooms, floors, buildings, or cities.

9) What is APIPA?

Short for Automatic Private IP Addressing, a feature of later Windows operating systems. With APIPA, DHCP clients can automatically self-configure an IP address and subnet mask when a DHCPserver isn’t available. When a DHCP client boots up, it first looks for a DHCP server in order to obtain an IP address and subnet mask. If the client is unable to find the information, it uses APIPA to automatically configure itself with an IP address from a range that has been reserved especially for Microsoft. The IP address range is 169.254.0.1 through 169.254.255.254. The client also configures itself with a default class B subnet mask of 255.255.0.0. A client uses the self- configured IP address until a DHCP server becomes available.

The APIPA service also checks regularly for the presence of a DHCP server (every five minutes, according to Microsoft). If it detects a DHCP server on the network, APIPA stops, and the DHCP server replaces the APIPA networking addresses with dynamically assigned addresses.

APIPA is meant for non routed small business environments,
usually less than 25 clients.

10) What is an RFC? Name a few if possible (not necessarily the numbers, just the ideas behind them)

Short for Request for Comments, a series of notes about the Internet, started in 1969 (when the Internet was the ARPANET). An Internet Document can be submitted to the IETF by anyone, but the IETF decides if the document becomes an RFC. Eventually, if it gains enough interest, it may evolve into an Internet standard.
Each RFC is designated by an RFC number. Once published, an RFC never changes. Modifications to an original RFC are assigned a new RFC number.

11) What is RFC 1918?

RFC 1918 is Address Allocation for Private Internets The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the
IP address space for private internets: 10.0.0.0 –

10.255.255.255 (10/8 prefix) 172.16.0.0 – 172.31.255.255
(172.16/12 prefix) 192.168.0.0 – 192.168.255.255
(192.168/16 prefix) We will refer to the first block as “24-bit block”, the second as “20-bit block”, and to the third as “16-bit” block. Note that (in pre-CIDR notation) the first block is nothing but a single class A network number, while the second block is a set of 16 contiguous class B network numbers, and third block is a set of 256 contiguous class C network numbers.


12) What is CIDR?

CIDR (Classless Inter-Domain Routing, sometimes known as supernetting) is a way to allocate and specify the Internet addresses used in inter-domain routing more flexibly than with the original system of Internet Protocol (IP) address classes. As a result, the number of available Internet addresses has been greatly increased.

13. You have the following Network ID:
192.115.103.64/27.What is the IP range for your network?

It ranges from 192.115.103.64 – 192.115.103.96

But the usable address are from 192.115.103.64 –
192.115.103.94

192.115.103.95 – it is the broadcast address
192.115.103.96 – will be the ip address of next range

we can use 30 hosts in this network

14.You have the following Network ID: 131.112.0.0. You need at least 500 hosts per network. How many networks can you create? What subnet mask will you use?

If you need 500 users then 2^9th would give you 512 (remember the first and last are network and broadcast), 510 usable. So of your 32 bits you would turn the last 9 off for host and that would give you give you a 255.255.254.0 subnet mask
(11111111.11111111.11111110.00000000).
Now that we know that

we can see that you have the first 7 of your third octet turned on so to figure out how many subnets you have us the formula
2^7th= 128. So you can have 128 subnets with 500 people on them.

15.You need to view at network traffic. What will you use? Name a few tools

winshark or tcp dump , or ethereal (available in our file server)

16. How do I know the path that a packet takes to the destination?

use “tracert” command-line


17. What does the ping 192.168.0.1 -l 1000 -n 100 command do?

The ping command will send roundtrip packets to a destination ( other PC, router, printer, etc. ) and see how long it takes. The 192.168.0.1
is the destination ( which, by the way is a typical default IP address of a router. ) The -l 1000 is how big the packet should be in bytes. The default is 32, if the -l parameter is not used. And the -n 100 is saying to send it 100 times. The default is 4, when this parameter is not used.

18. What is DHCP? What are the benefits and drawbacks of using it?

Benefits:


1. DHCP minimizes configuration errors caused by manual IP address configuration.


2. Reduced network administration.

Disadvantage

Your machine name does not change when you get a new IP address. The DNS (Domain Name System) name is associated with your IP address and therefore does change. This only presents a problem if other clients try to access your machine by its DNS name.



19.Describe the steps taken by the client and DHCP server in order to obtain an IP address.

*  At least one DHCP server must exist on a network.

Once the DHCP server software is installed, you create a DHCP scope, which is a pool of IP addresses that the server manages. When clients log on, they request an IP address from the server, and the server provides an IP address from its pool of available addresses.
* DHCP was originally defined in RFC 1531 (Dynamic Host Configuration Protocol, October 1993) but the most recent update is RFC 2131 (Dynamic Host Configuration Protocol, March 1997). The IETF Dynamic Host Configuration (dhc) Working Group is chartered to produce a protocol for automated allocation, configuration, and management of IP addresses and TCP/IP protocol stack parameters.


20. What is the DHCPNACK and when do I get one? Name 2 scenarios.

Recently I saw a lot of queries regarding when the Microsoft DHCP server issues a NAK to DHCP clients.For simplification purposes, I am listing down the possible scenarios in which the server should NOT issue a NAK. This should give you a good understanding of DHCP NAK behavior.When a DHCP server receives a DHCPRequest with a previously assigned address specified, it first checks to see if it came from the local segment by checking the GIADDR field. If it originated from the local segment, the DHCP server compares the requested address to the IP address and subnet mask belonging to the local interface that received the request.
DHCP server will issue a NAK to the client ONLY IF it is sure that the client, “on the local subnet”, is asking for an address that doesn’t exist on that subnet.The server will send a NAK EXCEPT in the following scenarios:-


1. Requested address from possibly the same subnet but not in the address pool of the server:-

This can be the failover scenario in which 2 DHCP servers are serving the same subnet so that when one goes down, the other should not NAK to clients which got an IP from the first server.


2. Requested address on a different subnet:-
If the Address is from the same superscope to which the subnet belongs, DHCP server will ACK the REQUEST.


21. What ports are used by DHCP and the DHCP clients?

Requests are on UDP port 68, Server replies on UDP 67


22. Describe the process of installing a DHCP server in an AD infrastructure.

Use Add/Remove program wizard . . .


23. What is DHCPINFORM?

DHCPInform is a DHCP message used by DHCP clients to obtain DHCP options. While PPP remote access clients do not use DHCP to obtain IP addresses for the remote access connection, Windows 2000 and Windows 98 remote access clients use the DHCPInform message to obtain DNS server IP addresses, WINS server IP addresses, and a DNS domain name. The DHCPInform message is sent after the IPCP negotiation is concluded. The DHCPInform message received by the remote access server is then forwarded to a DHCP server. The remote access server forwards DHCPInform messages only if it has been configured with the DHCP Relay Agent..

24. Describe the integration between DHCP and DNS.

Traditionally, DNS and DHCP servers have been configured and managed one at a time. Similarly, changing authorization rights for a particular user on a group of devices has meant visiting each one and making configuration changes. DHCP integration with DNS allows the aggregation of these tasks across devices, enabling a company’s network services to scale in step with the growth of network users, devices, and policies, while reducing administrative operations and costs.

This integration provides practical operational efficiencies that lower total cost of ownership. Creating a DHCP network automatically creates an associated DNS zone, for example, reducing the number of tasks required of network administrators. And integration of DNS and DHCP in the same database instance provides unmatched consistency between service and management views of IP address-centric network services data.

25.What options in DHCP do you regularly use for an MS network?

Automatic providing IP address

Subnet mask

DNS server

Domain name

Default getaway or router

26. What are User Classes and Vendor Classes in DHCP?

Microsoft Vendor Classes

The following list contains pre-defined vendor classes that are available in Windows 2000 DHCP server.


Class Data Class Name Description MSFT 5.0 Microsoft Windows
2000 options Class that includes all Windows 2000 DHCP
clients. MSFT 98 Microsoft
Windows 98 options Class that includes all Windows 98 and
Microsoft Windows Millennium Edition (Me) DHCP clients. MSFT
Microsoft options Class that includes
all Windows 98, Windows Me, and Windows 2000 DHCP clients.
If you have non-Microsoft DHCP clients, you can define other vendor-specific classes on the DHCP server. When you define such classes, make sure the vendor class identifier that you define matches the identifier used by the clients.


User Classes

The following list contains pre-defined user classes that
are available in Windows 2000 DHCP server.

Collapse this tableExpand this table

Class ID Class Type Description Unspecified Default user
class All DHCP clients that have no user class specified.
RRAS.Microsoft Default Routing and Remote Access class All Dial-Up Networking (DUN) clients. Bootp Default Bootp class All Bootp clients

In addition to these pre-defined classes, you can also add custom user classes for Windows 2000 DHCP clients. When you configure such classes, you must specify a custom identifier that corresponds to the user
class defined on the DHCP server.

27.How do I configure a client machine to use a specific User Class?

The command to configure a client machine to use a specific user class is

ipconfig /setclassid “<Name of your Network card>” <Name of the class you created on DHCP and you want to join (Name is case sensitive)>

Eg:

ipconfig /setclassid ” Local Area Network” Accounting


28. What is the BOOTP protocol used for, where might you find it in Windows network infrastructure?

BootP (RFC951) provides

* a unique IP address to the requester (using port 67) similar to the DHCP request on port 68 AND
* can provide (where supported) the ability to boot a system without a hard drive (ie: a diskless client)

Apple OS X 10.* Server supports BootP (albeit) renamed as NetBoot. The facility allows the Admin to maintain a selected set of configurations as boot images and then assign sets of client systems to share(or boot from) that image. For example Accounting, Management, and Engineering departments have elements in common, but which can be unique from other
departments. Performing upgrades and maintenance on three images is far more productive that working on all client systems individually.

Startup is obviously network intensive, and beyond 40-50 clients, the Admin needs to carefully subnet the infrastructure, use gigabit switches, and host the images local to the clients to avoid saturating the network. This will expand the number of BootP servers and multiply the number of images, but the productivity of 1 BootP server per 50 clients is
undeniable 🙂

Sunmicro, Linux, and AIX RS/600 all support BootP.

To date, Windows does not support booting “diskless clients”.



29. DNS zones – describe the differences between the 4 types.


Dns zone is actual file which contains all the records for a specific domain.

i)Forward Lookup Zones :-

This zone is responsible to resolve host name to ip.

ii)Reverse Lookup Zones :-

This zone is responsible to resolve ip to host name.

iii)Stub Zone :-

Stubzone is read only copy of primary zone.but it contains
only 3 records viz

the SOA for the primary zone, NS record and a Host (A) record.

30. DNS record types – describe the most important ones. Type of Record What it does

A (Host) Classic resource record. Maps hostname to IP(ipv4)

PTR Maps IP to hostname (Reverse of A (Host)

AAAA Maps hostname to ip (ipv6)

Cname Canonical name, in plain English an alias.such as Web Server,FTP Server, Chat Server

NS Identifies DNS name servers. Important for forwarders

MX Mail servers, particularly for other domains.MX records required to deliver internet email.

_SRV Required for Active Directory. Whole family of underscore service,records, for example, gc = global catalog.

SOA Make a point of finding the Start of Authority (SOA) tab at the
DNS Server.



31. Describe the process of working with an external domain name

Serving Sites with External Domain Name Servers  , If you host Web sites on this server and have a standalone DNS server acting as a primary (master) name server for your sites, you may want to set up your control panel’s DNS server to function as a secondary (slave) name server:

To make the control panel’s DNS server act as a secondary name server:

1. Go to Domains > domain name > DNS Settings (in the Web Site group).
2. Click Switch DNS Service Mode.
3. Specify the IP address of the primary (master) DNS server.
4. Click Add.
5. Repeat steps from 1 to 5 for each Web site that needs to have a secondary name server on this machine.

To make the control panel’s DNS server act as a primary for a zone:

1. Go to Domains > domain name > DNS Settings (in the Web Site group).
2. Click Switch DNS Service Mode. The original resource records for the zone will be restored.

If you host Web sites on this server and rely entirely on other machines to perform the Domain Name Service for your sites (there are two external name servers – a primary and a secondary), switch off the control panel’s DNS service for each site served by external name servers.

To switch off the control panel’s DNS service for a site
served by an external name server:

1. Go to Domains > domain name > DNS Settings (in the Web Site group).
2. Click Switch Off the DNS Service in the Tools group.
Turning the DNS service off for the zone will refresh the screen, so that only a list of name servers remains.

Note: The listed name server records have no effect on the system. They are only presented on the screen as clickable links to give you a chance to validate the configuration of the zone maintained on the external authoritative name servers.

1. Repeat the steps from 1 to 3 to switch off the local domain name service for each site served by external name servers.

If you wish to validate the configuration of a zone maintained on authoritative name servers:

1. Go to Domains > domain name > DNS Settings (in the Web Site group).
2. Add to the list the entries pointing to the
appropriate name servers that are authoritative for the zone: click Add, specify a name server, and click OK. Repeat this for each name server you would like to test. The records will appear in the list.

1. Click the records that you have just created. Parallels Plesk Panel will retrieve the zone file from a remote name server and check the resource records to make sure that domain’s resources are properly resolved.

The results will be interpreted and displayed on the screen.


32. Describe the importance of DNS to AD.

When you install Active Directory on a server, you promote the server to the role of a domain controller for a specified domain. When completing this process, you are prompted to specify a DNS domain name for the Active Directory domain for which you are joining and promoting the server.If during this process, a DNS server authoritative for the domain that you
specified either cannot be located on the network or does not support the DNS dynamic update protocol, you are prompted with the option to install a DNS server. This option is provided because a DNS server is required to locate this server or other domain controllers for members of an Active Directory domain

33.Describe a few methods of finding an MX record for a remote domain on the Internet.

In order to find MX Records for SMTP domains you can use Command-line tools such as NSLOOKUP or DIG. You can also use online web services that allow you to perform quick searches and display the information in a convenient manner.

34. What does “Disable Recursion” in DNS mean?

In the Windows 2000/2003 DNS console (dnsmgmt.msc), under a server’s Properties -> Forwarders tab is the setting Do not use recursion for this domain. On the Advanced tab you will find the confusingly similar option Disable recursion (also disables forwarders).

Recursion refers to the action of a DNS server querying additional DNS servers (e.g. local ISP DNS or the root DNS servers) to resolve queries that it cannot resolve from its own database


35. What could cause the Forwarders and Root Hints to be grayed out?

Win2K configured your DNS server as a private root server


36. What is a “Single Label domain name” and what sort of issues can it cause?

Single-label names consist of a single word like “contoso”.

• Single-label DNS names cannot be registered by using an Internet registrar.
• Client computers and domain controllers that joined to single-label domains require additional configuration to ynamically register DNS records in
single-label DNS zones. • Client computers and domain controllers may require additional configuration to resolve DNS queries in single-label DNS zones.
• By default, Windows Server 2003-based domain members, Windows XP-based domain members, and Windows 2000-based domain members do not perform dynamic updates to single-label DNS zones.
• Some server-based applications are incompatible with single-label domain names. Application support may not exist in the initial release of an application, or support may be dropped in a future release. For example,
Microsoft Exchange Server 2007 is not supported in environments in which single-label DNS is
used.
• Some server-based applications are incompatible with the domain rename feature that is supported in Windows Server 2003 domain controllers and in Windows Server 2008 domain controllers. These incompatibilities either block or complicate the use of the domain rename feature when you try to rename a single-label DNS name to a fully qualified domain name.

37. What is the “in-addr.arpa” zone used for?

When creating DNS records for your hosts, A records make sense. After all, how can the world find your mail server unless the IP address of that server is associated with its hostname within a DNS database? However, PTR records aren’t as easily understood. If you already have a zone file, why

does there have to be a separate in-addr.arpa zone containing PTR records matching your A records? And who should be making those PTR records–you or your provider? Let’s start by defining in-addr.arpa. .arpa is actually a TLD like .com or .org. The name of the TLD comes from Address and Routing Parameter Area and it has been designated by the IANA to be used exclusively for Internet infrastructure purposes. In other words, it is an important zone and an integral part of the inner workings of DNS. The
RFC for DNS (RFC 1035) has an entire section on the in-addr.arpa domain. The first two paragraphs in that section state the purpose of the domain: “The Internet uses a special domain to support gateway location and Internet address to host mapping. Other classes may employ a similar
strategy in other domains. The intent of this domain is to provide a guaranteed method to perform host address to host name mapping, and to facilitate queries to locate all gateways on a particular network in the Internet. Note that both of these services are similar to functions that could be performed by inverse queries; the difference is that this part of the domain name space is structured according to address, and hence can guarantee that the appropriate data can be located without an exhaustive search of the domain space.” In other words, this zone provides a database of all allocated networks and the DNS reachable hosts within those networks. If your assigned network does not appear in this zone, it appears to be unallocated. And if your hosts don’t have a PTR record in this database, they appear to be unreachable through DNS. Assuming an A record exists for a host, a missing PTR record may or may not impact on the DNS reachability of that host, depending upon the applications running on that host. For example, a mail server will definitely be impacted as PTR records are used in mail header checks and by most anti-SPAM mechanisms. Depending upon your web server configuration, it may also depend upon an existing PTR record. This is why the DNS RFCs recommend that every A record has an associated PTR record. But who should make and host those PTR records? Twenty years ago when you could buy a full Class C network address (i.e. 254 host addresses) the answer was easy: you. Remember, the in-addr.arpa zone is concerned with delegated network addresses. In other words, the owner of the network address is authoritative (i.e. responsible) for the host PTR records associated with that network address space. If you only own one or two host addresses within a network address space, the provider you purchased those addresses from needs to host your PTR records as the provider is the owner of (i.e. authoritative for) the network address. Things are a bit more interesting if you have been delegated a CIDR block of addresses. The in-addr.arpa zone assumes a classful addressing scheme where a Class A address is one octet (or /8), a Class B is 2 octets (or /16) and a Class C is 3 octets (or /24). CIDR allows for delegating address space outside of these boundaries–say a /19 or a /28. RFC 2317 provides a best current practice for maintaining in-addr.arpa with these types of network allocations. Here is a summary regarding PTR records: • Don’t wait until users complain about DNS unreachability–be proactive and ensure there is an associated PTR record for every A record. • If your provider hosts your A records, they should also host your PTR records. • If you only have one or two assigned IP addresses, your provider should host your PTR records as they are authoritative for the network those hosts belong to. • If you own an entire network address (e.g. a Class C
address ending in 0), you are responsible for hosting your PTR records. • If you are configuring an internal DNS server within the private address ranges (e.g. 10.0.0.0 or
192.168.0.0), you are responsible for your own internal PTR records. • Remember: the key to PTR hosting is knowing who is authoritative for the network address for your domain. When in doubt, it probably is not you.


38. What are the requirements from DNS to support AD?
When you install Active Directory on a member server, the member server is promoted to a domain controller. Active Directory uses DNS as the location mechanism for domain controllers, enabling computers on the network to obtain IP addresses of domain controllers. During the installation of Active Directory, the service (SRV) and address (A) resource records are dynamically registered in DNS, which are necessary for the successful functionality of the domain controller locator (Locator) mechanism.
To find domain controllers in a domain or forest, a client queries DNS for the SRV and A DNS resource records of the domain controller, which provide the client with the names and IP addresses of the domain controllers. In this context, the SRV and A resource records are referred to as Locator DNS resource records. When adding a domain controller to a forest, you are updating a DNS zone hosted on a DNS server with the Locator DNS resource records and identifying the domain controller. For this reason, the DNS zone must allow dynamic updates (RFC 2136) and the DNS server hosting that zone must support the SRV resource records (RFC 2782) to advertise the Active Directory directory service. For more information about RFCs, see DNS RFCs.

If the DNS server hosting the authoritative DNS zone is not a server running Windows 2000 or Windows Server 2003, contact your DNS administrator to determine if the DNS server supports the required standards. If the server does not support the required standards, or
the authoritative DNS zone cannot be configured to allow dynamic updates, then modification is required to your existing DNS infrastructure.

39. How do you manually create SRV records in DNS?
this is on windows server

go to run —> dnsmgmt.msc

rightclick on the zone you want to add srv record to and choose “other new record” and choose service location(srv)…..


40. Name 3 benefits of using AD-integrated zones.

1. you can give easy name resolution to ur clients.

2. By creating AD- integrated zone you can also trace hacker and spammer by creating reverse zone.

3. AD integrated zoned all for incremental zone transfers which on transfer changes and not the entire zone. This reduces zone transfer traffic.

4. AD Integrated zones suport both secure and dmanic updates.

5. AD integrated zones are stored as part of the active directory and support domain-wide or forest-wide replication through application pertitions in AD.

41. What are the benefits of using Windows 2003 DNS when using AD-integrated zones?

Advantages:

DNS supports Dynamic registration of SRV records registered by a Active Directory server or a domain controller during  promotion. With the help of SRV records client machines can find domain controllers in the network.

1. DNS supports Secure Dynamic updates. Unauthorized access is denied.

2. Exchange server needs internal DNS or AD DNS to locate Global Catalog servers.

3. Active Directory Integrated Zone. If you have more than
one domain controller (recommended) you need not worry about
zone replication. Active Directory replication will take care of DNS zone replication also.

4. If your network use DHCP with Active Directory then no other DHCP will be able to service client requests coming from different network. It is because DHCP server is authorized in AD and will be the only server to participate on network to provide IP Address information to client machines.

5. Moreover, you can use NT4 DNS with Service Pack 4 or later. It supports both SRV record registration and Dynamic Updates.

Using Microsoft DNS gives the following benefits:
If you implement networks that require secure updates.
If you want to take benefit of Active Directory replication.
If you want to integrate DHCP with DNS for Low-level clients
to register their Host records in Zone database.


42. You installed a new AD domain and the new (and first) DC has not registered its SRV records in DNS. Name a few possible causes.

The machine cannot be configured with DNS client her own
The DNS service cannot be run


43. What are the benefits and scenarios of using Stub zones?

One of the new features introduced in the Windows Server 2003-based implementation of DNS are stub zones. Its main purpose is to provide name resolution in domains, for which a local DNS server is not authoritative. The stub zone contains only a few records:

– Start of Authority (SOA)
record pointing to a remote DNS server that is considered to be the best source of information about the target DNS domain, – one or more Name Server (NS) records (including the entry associated with the SOA record), which are authoritative for the DNS domain represented by the stub zone, – corresponding A records for each of the NS entries (providing IP addresses of the servers). While you can also provide name resolution for a remote domain by either creating a secondary zone (which was a common approach in
Windows Server 2000 DNS implementation) or delegation (when dealing with a contiguous namespace), such approach forces periodic zone transfers, which are not needed when stub zones are used. Necessity to traverse network in order to obtain individual records hosted on the remote Name Servers is mitigated to some extent by caching process, which keeps them on the local server for the duration of their Time-to-Live (TTL) parameter. In addition, records residing in a stub zone are periodically validated and refreshed in order to avoid lame delegations.

44. What are the benefits and scenarios of using Conditional Forwarding?

45. What are the differences between Windows Clustering, Network Load Balancing and Round Robin, and scenarios for each use?

I will make a few assumptions here:

1) By “Windows Clustering Network Load Balancing” you mean Windows Network
Load Balancing software included in Windows Server software a.k.a NLB., and
2) By Round Robin, you mean DNS Round Robin meaning the absence of a software or hardware load balancing device, or the concept of the Round Robin algorithm available in just about every load balancing solution.


Microsoft NLB is designed for a small number (4 – 6) of Windows Servers and a low to moderate number of new connections per second, to provide distribution of web server requests to multiple servers in a virtual resource pool. Some would call this a “cluster”, but there are suttle differences between a clustered group of devices and a more loosely configured virtual pool. From the standpoint of scalability and performance, almost all hardware load balancing solutions are superior to this and other less known software load balancing solutions [e.g. Bright Tiger circa 1998].

DNS Round Robin is an inherent load balancing method built into DNS. When you resolve an IP address that has more than one A record, DNS hands out different resolutions to different requesting local DNS servers. Although there are several factors effecting the exact resulting algorithm (e.g. DNS caching, TTL, multiple DNS servers [authoritative or cached]), I stress the term “roughly” when I say it roughly results in an even distribution of resolutions to each of the addresses specified for a particular URL. It does not however, consider availability, performance, or any other metric and is completely static. The basic RR algorithm is available in many software and hardware load balancing solutions and simply hands the next request to the next resource and starts back at the first resource when it hits the last one.

NLB is based on proprietary software, meant for small groups of Windows servers only on private networks, and is dynamic in nature (takes into account availability of a server, and in some cases performance). “Round Robin”, DNS or otherwise, is more generic, static in nature (does not take into account anything but the resource is a member of the resource pool and each member is equal), and ranges from DNS to the default static load balancing method on every hardware device in the market.

46. How do I work with the Host name cache on a client computer?





47. How do I clear the DNS cache on the DNS server?
To clear the server names cache

* Using the Windows interface

* Using a command line

Using the Windows interface

1. Open DNS.

2. In the console tree, click the applicable DNS server.

Where?

* DNS/applicable DNS server

3. On the Action menu, click Clear Cache.

Notes

* To perform this procedure, you must be a member of the Administrators group on the local computer, or you must have been delegated the appropriate authority. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure.

* To open DNS, click Start, click Control Panel,
double-click Administrative Tools, and then double-click DNS.

Using a command line

1. Open Command Prompt.

2. Type the following command and then press ENTER:

Dnscmd ServerName /clearcache


48. What is the 224.0.1.24 address used for?


WINS server group address. Used to support autodiscovery and dynamic configuration of replication for WINS servers. For more information, see WINS replication overview  WINS server group address. Used to support autodiscovery and  dynamic configuration of replication for WINS servers.

49. What is WINS and when do we use it?

In the Windows Server family, the primary means for client computer to locate and communicate with other computers on an Internet Protocol (IP) network is by using Domain Name
System (DNS). However, clients that use older versions of Windows, such as Windows NT 4.0, use network basic I/O system (NetBIOS) names for network communication. Some applications that run on Windows Server 2003 may also use NetBIOS names for network communication. Using NetBIOS names requires a method of resolving NetBIOS names to IP . Using a WINS server is essential for any Windows client computer to work with other Windows computers over the Internet. In addition, using a WINS server is essential for any Windows client computer at Indiana University that intends to use Microsoft network resources. To use WINS services, you must insert into your TCP/IP networking configuration the IP address of the WINS servers you wish to use.

50. Can you have a Microsoft-based network without any WINS server on it? What are the “considerations” regarding not using WINS?


51. Describe the differences between WINS push and pull replications.

To replicate database entries between a pair of WINS servers, you must configure each WINS server as a pull partner, a push partner, or both with the other WINS server.

* A push partner is a WINS server that sends a message to its pull partners, notifying them that it has new WINS database entries. When a WINS server’s pull partner responds to the message with a replication request, the WINS server sends (pushes) copies of its new WINS database entries (also known as replicas) to the requesting pull partner.
* A pull partner is a WINS server that pulls WINS database entries from its push partners by requesting any new WINS database entries that the push partners have. The pull partner requests the new WINS database entries that have a higher version number than the last entry the pull
partner received during the most recent replication.

52. What is the difference between tombstoning a WINS record and simply deleting it?

Simple deletion removes the records that are selected in the WINS console only from the local WINS server you are currently managing. If the WINS records deleted in this way exist in WINS data replicated to other WINS servers on your network, these additional records are not fully removed.
Also, records that are simply deleted on only one server can reappear after replication between the WINS server where simple deletion was used and any of its replication partners. Tombstoning marks the selected records as tombstoned, that is, marked locally as extinct and immediately released from active use by the local WINS server. This method allows the tombstoned records to remain present in the server database for purposes of subsequent replication of these records to other servers. When the tombstoned records are replicated, the tombstone status is updated and applied by other WINS servers that store replicated copies of these records. Each replicating WINS server then updates and tombstones

53. Name the NetBIOS names you might expect from a Windows 2003 DC that is registered in WINS.

54. Describe the role of the routing table on a host and on
a router.

During the process of routing, decisions of hosts and routers are aided by a database of routes known as the routing table. The routing table is not exclusive to a router. Depending on the routable protocol, hosts may also have a routing table that may be used to decide the best router for the packet to be forwarded. Host-based routing tables are optional for the Internet Protocol, as well as  obsolete routable protocols such as IPX.

55. What are routing protocols? Why do we need them? Name a few.

A routing protocol is a protocol that specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network, the choice of the route being done by routing algorithms. Each router has a prior knowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network. For a discussion of the concepts behind routing protocols, see: Routing.

The term routing protocol may refer specifically to one operating at layer three of the OSI model, which similarly disseminates topology information between routers.

Many routing protocols used in the public Internet are defined in documents called RFCs.[1][2][3][4]

Although there are many types of routing protocols, two major classes are in widespread use in the Internet:
link-state routing protocols, such as OSPF and IS-IS; and
path vector or distance vector protocols, such as BGP, RIP
and EIGRP.



56. What are router interfaces? What types can they be?

Routers can have many different types of connectors; from Ethernet, Fast Ethernet, and Token Ring to Serial and ISDN ports.  Some of the available configurable items are logical addresses (IP,IPX), media types, bandwidth, and administrative commands.  Interfaces are configured in interface mode which you get to from global configuration mode after logging in.
The media type is Ethernet, FastEthernet, GigabitEthernet,
Serial, Token-ring, or other media types. You must keep in
mind that a 10Mb Ethernet interface is the only kind of Ethernet interface called Ethernet. A 100Mb Ethernet interface is called a FastEthernet interface and a 1000Mb Ethernet interface is called a GigabitEthernet interface.

57. In Windows 2003 routing, what are the interface filters?

58. What is NAT?

Windows Server 2003 provides network address translation (NAT) functionality as a part of the Routing and Remote Access service. NAT enables computers on small- to medium-sized organizations with private networks to access resources on the Internet or other public network. The
computers on a private network are configured with reusable  private Internet Protocol version 4 (IPv4) addresses; the computers on a public network are configured with globally unique IPv4 (or, rarely at present, Internet Protocol version 6 [IPv6]) addresses. A typical deployment is a small office or home office (SOHO), or a medium-sized businesss, that uses Routing and Remote Access NAT technology to enable computers on the internal corporate network to connect to resources on the Internet without having to deploy a proxy server.

59. What is the real difference between NAT and PAT?

Take NAT (Network Address Translation) and PAT (Port Address Translation). NAT allows you to translate or map one IP address onto another single ip address. PAT on the other hand is what is most commonly referred to as NAT. In a PAT system you have a single or group of public IP addresses that are translated to multiple internal ip addresses by mapping the TCP/UDP ports to different ports. This means that by using some “magic” on a router or server you can get around problems that you might have with two web browsers sending a request out the same port.

60. How do you configure NAT on Windows 2003?

http://www.windowsnetworking.com/articles_tutorials/NAT_Windows_2003_Setup_Configuration.html

Configure Routing and Remote Access

To activate Routing and Remote Access, follow these steps:

1. Click Start, point to All Programs, point to
Administrative Tools, and then click Routing and Remote Access.
2. Right-click your server, and then click Configure and
Enable Routing and Remote Access.
3. In the Routing and Remote Access Setup Wizard, click
Next, click Network address translation (NAT), and then
click Next.
4. Click Use this public interface to connect to the
Internet, and then click the network adapter that is
connected to the Internet. At this stage you have the option
to reduce the risk of unauthorized access to your network.
To do so, click to select the Enable security on the
selected interface by setting up Basic Firewall check box.
5. Examine the selected options in the Summary box, and
then click Finish.

Configure dynamic IP address assignment for private network
clients
You can configure your Network Address Translation computer
to act as a Dynamic Host Configuration Protocol (DHCP)
server for computers on your internal network. To do so,
follow these steps:

1. Click Start, point to All Programs, point to
Administrative Tools, and then click Routing and Remote Access.
2. Expand your server node, and then expand IP Routing.
3. Right-click NAT/Basic Firewall, and then click Properties.
4. In the NAT/Basic Firewall Properties dialog box, click the Address Assignment tab.
5. Click to select the Automatically assign IP addresses
by using the DHCP allocator check box. Notice that default
private network 192.168.0.0 with the subnet mask of
255.255.0.0 is automatically added in the IP address and the Mask boxes. You can keep the default values, or you can
modify these values to suit your network.
6. If your internal network requires static IP assignment for some computers — such as for domain controllers or for DNS servers — exclude those IP addresses from the DHCP pool. To do this, follow these steps:
1. Click Exclude.
2. In the Exclude Reserved Addresses dialog box,
click Add, type the IP address, and then click OK.
3. Repeat step b for all addresses that you want to exclude.
4. Click OK.

Configure name resolution
To configure name resolution, follow these steps:

1. Click Start, point to All Programs, point to
Administrative Tools, and then click Routing and Remote Access.
2. Right-click NAT/Basic Firewall, and then click Properties.
3. In the NAT/Basic Firewall Properties dialog box, click the Name Resolution tab.
4. Click to select the Clients using Domain Name System
(DNS) check box. If you use a demand-dial interface to
connect to an external DNS server, click to select the
Connect to the public network when a name needs to be
resolved check box, and then click the appropriate dial-up
interface in the list.





61. How do you allow inbound traffic for specific hosts on Windows 2003 NAT?

You can use the Windows Server 2003 implementation of IPSec to compensate for the limited protections provided by applications for network traffic, or as a network-layer foundation of a defense-in-depth strategy. Do not use IPSec as a replacement for other user and application security
controls, because it cannot protect against attacks from within established and trusted communication paths. Your authentication strategy must be well defined and implemented for the potential security provided by IPSec to be realized, because authentication verifies the identity and trust of the computer at the other end of the connection.

62. What is VPN? What types of VPN does Windows 2000 and beyond work with natively?

VPN gives extremely secure connections between private
networks linked through the Internet. It allows remote
computers to act as though they were on the same secure,
local network.

L2TP (layer 2 tunneling protocol )

vpn server is also know as L2TP server in native mode & in
PPTP in mixed mode


63. What is IAS? In what scenarios do we use it?

IAS is called as Internet Authentication Service. It’s used by for configuring centralised authentication using RADIUS server.

64. What’s the difference between Mixed mode and Native mode in AD when dealing with RRAS?

When you are in Mixed mode certain options in the dial-in tab of the user proeprties are disabled. And some of the RRAS policies are also disabled. So if you want high level security with all the advanced feature then change the AD to Native mode.

65. What is the “RAS and IAS” group in AD?

Used for managing security and allowing administration for the respective roles of the server.

66. What are Conditions and Profile in RRAS Policies?

The conditions and profiles are used to set some restrictions based on the media type, connection method, group membership and lot more. So if used matches those conditions mentioned in the profile then he can allowed /
denied access to RAS / VPN server.

67. What types or authentication can a Windows 2003 based RRAS work with?

It supports authentication methods like MSCHAPv2, MSCHAP, SPAP, EAP, Digest authentication. ( You can check it by going to properties of your server in RRAS )

68. How does SSL work?

Internet communication typically runs through multiple program layers on a server before getting to the requested data such as a web page or cgi scripts.

The outer layer is the first to be hit by the request. This is the high level protocols such as HTTP (web server), IMAP (mail server), and FTP (file transfer).

Determining which outer layer protocol will handle the request depends on the type of request made by the client. This high level protocol then processes the request through the Secure Sockets Layer. If the request is for a non-secure connection it passes through to the TCP/IP layer and the server application or data.

If the client requested a secure connection the ssl layer initiates a handshake to begin the secure communication process. Depending on the SSL setup on the server, it may require that a secure connection be made before allowing communication to pass through to the TCP/IP layer in which
case a non-secure request will send back an error asking for them to retry securely (or simply deny the non-secure
connection).

69. How does IPSec work?

IPSec is an Internet Engineering Task Force (IETF) standard suite of protocols that provides data authentication, integrity, and confidentiality as data is transferred between communication points across IP networks. IPSec provides data security at the IP packet level. A packet is a data bundle that is organized for transmission across a network, and it includes a header and payload (the data in the packet). IPSec emerged as a viable network security standard because enterprises wanted to ensure that data could be securely transmitted over the Internet. IPSec protects against possible security exposures by protecting data while in transit.

70. How do I deploy IPSec for a large number of computers?

Just use this program Server and Domain Isolation Using IPsec and Group Policy



71. What types of authentication can IPSec use?

Deploying L2TP/IPSec-based Remote Access

Deploying L2TP-based remote access VPN connections using Windows Server 2003 consists of the following:

* Deploy certificate infrastructure

* Deploy Internet infrastructure

* Deploy AAA infrastructure

* Deploy VPN servers

* Deploy intranet infrastructure

* Deploy VPN clients


* Implantar certificado infra-estrutura
* Implantar infra-estrutura Internet
* Implantar infra-estrutura AAA
* Implementar VPN servidores
* Implantar intranet infra-estrutura
* Implementar clientes VPN


72. What is PFS (Perfect Forward Secrecy) in IPSec?

In an authenticated key-agreement protocol that uses public key cryptography, perfect forward secrecy (or PFS) is the property that ensures that a session key derived from a set of long-term public and private keys will not be compromised if one of the (long-term) private keys is compromised in the future. Forward secrecy has been used as a synonym for perfect forward secrecy [1], since the term perfect has been controversial in this context. However, at least one reference [2] distinguishes perfect forward secrecy from forward secrecy with the additional property that an agreed key will not be compromised even if agreed keys derived from the same long-term keying material in a subsequent run are compromised.

73. How do I monitor IPSec?

To test the IPSec policies, use IPSec Monitor. IPSec Monitor (Ipsecmon.exe) provides information about which IPSec policy is active and whether a secure channel between computers is established.



74. Looking at IPSec-encrypted traffic with a sniffer. What packet types do I see?

You can see the packages to pass, but you can not see its
contents

IPSec Packet Types
IPSec packet types include the authentication header (AH) for data integrity and the encapsulating security payload (ESP) for data confidentiality and integrity. The authentication header (AH) protocol creates an envelope that provides integrity, data origin identification and protection against replay attacks. It authenticates every packet as a defense against session-stealing attacks. Although the IP header itself is outside the AH header, AH also provides limited verification of it by not allowing changes to the IP header after packet creation (note that this usually precludes the use of AH in NAT environments, which modify packet headers at the point of NAT). AH packets use IP protocol 51. The encapsulating security payload (ESP) protocol provides the features of AH (except for IP header authentication), plus encryption. It can also be used in a null encryption mode that provides the AH protection against replay attacks and other such attacks, without encryption or IP header
authentication. This can allow for achieving some of the benefits of IPSec in a NAT environment that would not ordinarily work well with IPSec. ESP packets use IP protocol 50.

75. What can you do with NETSH?

Netsh is a command-line scripting utility that allows you to, either locally or remotely, display, modify or script the network configuration of a computer that is currently running.

76. How do I look at the open ports on my machine?

Windows: Open a command prompt (Start button -> Run-> type
“cmd”), and type:
netstat -a

Linux: Open an SSH session and type:
netstat -an

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9 Comments »

  1. Syyed Sahab allah Tala App ki Ilim me din dugni taraqqi ata farmaya yeh notes hum logo ke liye bahut madadgar hai Allah aap apne piya Nabi ke sadke aap ke jayez tamman puri kare aur aap ko har bala aur tufan se salamt rakhe

    Like

    Comment by Mohammed shamim — July 27, 2011 @ 4:11 PM

  2. Syyed Sahab allah Tala App ki ilim me din dugni taraqqi ata farmaya yeh notes hum logo ke liye bahut madadgar hai Allah aap apne piyare Nabi ke sadke aap ke jayez tamman puri kare aur aap ko har bala aur tufan se salamt rakhe

    Like

    Comment by Mohammed shamim — July 27, 2011 @ 4:13 PM

  3. Assalam,

    Awesome work ….!! Very useful information …

    I am unable to find a link for “Technical Interview Questions (Part 3/3)” could you please help me with that link…!

    Thanks a lot for sahring very useful information …!

    Regards,
    Mohasin

    Like

    Comment by Mohasin — March 13, 2012 @ 10:50 PM

  4. me to unable to find 3/3 link

    Like

    Comment by mohankumarv — May 23, 2012 @ 3:10 PM

  5. […] Technical Interview Questions (Part 1/3) [Networking] Edited & Maintained by SYED JAHANZAIB / a… Filed under: General IT Related — Syed Jahanzaib / Pinochio~:) @ 6:33 AM […]

    Like

    Pingback by General Network Engineer Interview Questions General Knowledge Questions « Yogesh(Yogi) — June 6, 2012 @ 1:32 AM

  6. Salam; Can I have some Group Policy Questions like Active Directory. Shukran…. Shoaib Lat

    Like

    Comment by Shoaib Lat — April 12, 2014 @ 6:35 AM

  7. Thanks for ur brief answer Send telecom interview q and a link in my mail id

    Like

    Comment by magesh — June 21, 2014 @ 12:29 PM

  8. Please share some scenario upon L2tp VPN server for remote access clients.

    Like

    Comment by umairmian — February 18, 2016 @ 5:46 PM


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