Network interview Questions and Answers - Set 1

1    Question No 1.  Is routing involved in communication between a PC and it’s gateway .

Answer : No.

Explanation : Routing is used to communicate between two different networks. Here the pc and it’s gateway are working in same network. So, there is no need for routing.

Question No 2. How many gateways can a PC have?

Answer : Depends on how many network you are going to use.

Explanation : In windows you can confire multiple number of ip and gateways in TCP/IP advanced option.

Question No 3. What is the use of VLAN.

Answer : To create virtual broadcast network.

Explanation :

i. Performance : In networks where traffic consists of a high percentage of broadcasts and multicasts, VLAN's can reduce the need to send such traffic to unnecessary destinations.

ii.Reduced cost : VLAN's can be used to create broadcast domains which eliminate the need for expensive routers.

iii. Security : Periodically, sensitive data may be broadcast on a network. In such cases, placing only those users who can have access to that data on a VLAN can reduce the chances of an outsider gaining access to the data

Question No 4. Can Windows XP be configured as a router.

Answer : Yes. 

Explanation : Configure two network interface card with two different ip address and do not set any default gateway for both interface.

Goto Run – type “ regedit.msc” -        HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesTcpipParameters

Right click IPEnableRouter registry object, and click Modify.

The IPEnableRouter window will appear. Type 1 as Value data and click OK.

After all this reboot the windows machine.

After rebooting, you can communicate between the networks.

Question No 5. Give two examples of protocols which use broadcasting.

Answer : ARP – request, DHCP discover.

Question No 6. How do vlans control broadcasting.

Answer : Each vlans are separate broadcast domain(network). Broadcasting will not happened between the networks. 

Question No 7. Why is a router required for communication between vlans.?

Answer : Each vlans are separate broadcast domain. Router is required to communicate the between the different broadcast domain.

Question No 8. What is the use of a TTL value in a IP header.

Answer : Time-to-live (TTL) is a value in an Internet Protocol (IP) packet that tells a network router, How long the packet should travel in network and when should be discarded. 

For a number of reasons, packets may not get delivered to their destination in a reasonable length of time. 

For example, a combination of incorrect routing tables could cause a packet to loop endlessly. A solution is to discard the packet after a certain time and send a message to the originator, who can decide whether to resend the packet. The initial TTL value is set, usually by a system default, This is 8-bit field. The TTL value range is 0-255.

Question No 9. What is the difference between a default route and a default gateway.?

Answer : Default gateway is usually used on switches that are not L3 switches/routers or on "hosts".  It just points to a router that "knows" how to get out.

The term "Default Route" usually means "ip route 0.0.0.0 0.0.0.0 x.x.x.x" or "default-information originate".  And means, if you don't have a "more specific" route, then send it to x.x.x.x, and that router will take care of it.

Question No 10.Can subnet masks be used in classful addressing protocols.

Answer : Yes. For class A – 255.0.0.0 Class B – 255.255.0.0 Class C – 255.255.255.0