Routing Interview Questions And Answers Essay.

Question 1

Task1. Multiple and short answer questions - Choose the most correct answer and explain it in your own words in the space provided below:

1.Which of the following statements is true regarding the command ip route 172.16.4.0 255.255.255.0 192.168.4.2?

1.The command is used to establish a static route.

2.The default administrative distance is used.

3.The command is used to configure the default route.

4.The subnet mask for the source address is 255.255.255.0.

A.1 and 2.

B.2 and 4.

4. 3 and 4.

D.All of the above.

2. Which command displays RIP routing updates?

A.Show ip route.

B.Debug ip rip.

C.Show protocols.

D.Debug ip route.

3. Which statement is true regarding classless routing protocols?

1.The use of discontiguous networks is not allowed.

2.The use of variable length subnet masks is permitted.

3.RIPv1 is a classless routing protocol.

4.IGRP supports classless routing within the same autonomous system.

5.RIPv2 supports classless routing.

A.1, 3 and 5.

B.3 and 4.

C.2 and 5.

D.None of the above.

4.You have the following routing table. Which of the following networks will not be placed in the neighbor routing table?

R   192.168.30.0/24 [120/1] via 192.168.40.1, 00:00:12, Serial0.

C   192.168.40.0/24 is directly connected, Serial0.

     172.16.0.0/24 is subnetted, 1 subnets.

C   172.16.30.0 is directly connected, Loopback0.

R   192.168.20.0/24 [120/1] via 192.168.40.1, 00:00:12, Serial0.

R   10.0.0.0/8 [120/15] via 192.168.40.1, 00:00:07, Serial0.

C   192.168.50.0/24 is directly connected, Ethernet0.

A.172.16.30.0.

B.192.168.30.0.

C.10.0.0.0.

D.All of them will be placed in the neighbor routing table.

5.What is split horizon?

A.Information about a route should not be sent back in the direction from which the original update came.

B.It splits the traffic when you have a large bus (horizon) physical network.

C.It holds the regular updates from broadcasting to a downed link.

D.It prevents regular update messages from reinstating a route that has gone down.

6.What command is used to stop RIP routing updates from exiting out an interface but still allow the interface to receive RIP route updates?

A.Router(config-if)# no routing.

B.Router(config-if)# passive-interface.

C.Router(config-router)# passive-interface s0.

D.Router(config-router)# no routing updates.

7.Two connected routers are configured with RIP routing. What will be the result when a router receives a routing update that contains a higher-cost path to a network already in its routing table?

A.The updated information will be added to the existing routing table.

B.The update will be ignored and no further action will occur.

C.The updated information will replace the existing routing table entry.

D.The existing routing table entry will be deleted from the routing table and all routers will exchange routing updates to reach convergence.

8.You type debug ip rip on your router console and see that 172.16.10.0 is being advertised to you with a metric of 16. What does this mean?

A.The route is 16 hops away.

B.The route has a delay of 16 microseconds.

C.The route is inaccessible.

D.The route is queued at 16 messages a second.

9.The Corporate router receives an IP packet with a source IP address of 192.168.214.20 and a destination address of 192.168.22.3. Looking at the output from the Corporate router, what will the router do with this packet?

Corp#sh ip route

[output cut]

R   192.168.215.0 [120/2] via 192.168.20.2, 00:00:23, Serial0/0.

R   192.168.115.0 [120/1] via 192.168.20.2, 00:00:23, Serial0/0.

R   192.168.30.0 [120/1] via 192.168.20.2, 00:00:23, Serial0/0.

C   192.168.20.0 is directly connected, Serial0/0.

C   192.168.214.0 is directly connected, FastEthernet0/0.

A.The packet will be discarded.

B.The packet will be routed out the S0/0 interface.

C.The router will broadcast looking for the destination.

D.The packet will be routed out the Fa0/0 interface.

10.If your routing table has a static, a RIP, and an IGRP route to the same network, which route will be used to route packets by default?

A.Any available route.

B.RIP route.

C.Static route.

D.IGRP route.

E.They will all load-balance.

11.What is route poisoning?

A.It sends back the protocol received from a router as a poison pill, which stops the regular updates.

B.It is information received from a router that can't be sent back to the originating router.

C.It prevents regular update messages from reinstating a route that has just come up.

D.It describes when a router sets the metric for a downed link to infinity.

Question 1

Task 1:

Response to Question 1:

Correct option is A.

Explanation: Subnet mask are used to mask remote network and not default routes. As there is no number at the end of the static route therefore default administrative distance is used.

Response to Question 2:

Correct option is B.

Explanation: The Internet protocol (IP) as well as the Routing Information Protocol that is received or sent by router can be displayed by debug ip rip command.

Response to Question 3:

Correct option is C.

Explanation: There is a fine difference between classful and classless routing protocols. In classful protocols, subnet mask is not send with updates whereas in classless protocols subnet masks are send along with updates. Classless routing protocols allows the use of variable length subnet mask. Between the two versions of routing information protocols RIPv2 supports classless routing.

Response to Question 4:

Correct option is C.

Explanation: Routing Information Protocols networking does not allow 16 hops and if the network 10.0.0.0 is placed in the next routing table then it will exceed 15 hops. This is not valid.

Response to Question 5:

Correct option is A.

Explanation: Split horizon is the process of preventing loops in routing methods. The principle that is followed is that routing information cannot be send back in the same direction from where it has been received.  

Response to Question 6:

Correct option is C.

Explanation: The passive interface will not let the updates to be sent to serial0 however, it allows to routing information protocols updates to be sent to serial0.

Response to Question 7:

Correct option is B.

Explanation: The administrative distance is checked first when the router receives a routing update and the route with the lowest AD is chosen. However, if the router receives two routes with the same administrative distance, then the route with the lowest metrics or hop count will be chosen.

Response to Question 8:

Correct option is C.

Explanation: 16 hops in routing information protocol network cannot be set as default. If a route with metric 16 is advertised, then it is not accessible.

Response to Question 9:

Correct option is A.

Explanation: No route of the IP address 192.168.214.20 is found in the routing table. Therefore, the packet will be discarded and a message will be send by ICMP destination.

Response to Question 10:

Correct option is C.

Explanation: Static route is used to route packets by default. The administrative distance of static route is 1 by default. Static route will be used over any other route if the default is not changed. The administrative distance of IGRP is 100 and that of RIP is 120, by default.

Response to Question 11:

Correct option is D.

Explanation: Route poisoning is the method by which invalid data packets are prevented from being send to the network. The distance vector routing protocol does this when an invalid data packet or large routing loops are identified. If the maximum capacity of the route is exceeded then the route will not be reachable. Therefore, the network is informed about the invalid path by the routing protocol by saying that the hop count is exceeding the maximum allowable.

Question 2

Response to Question 12:

Correct option is C.

Explanation: Routing information protocol version 2 and version 1 has the same timers and administrative distance. RIPv2 and RIP v1 is configured in the same way.

Response to Question 13:

Correct option is B.

Explanation: The administrative distance of routing information protocol is 120, whereas that of IGRP is 100. Therefore, the router will discard administrative address higher than 100.

Response to Question 14:

Correct option is C.

Explanation: Routing information protocol version 2 uses Split horizon and Hold-down timers to prevent routing loops. RIPv2 uses the same things as RIPv1 only difference is that RIPv2 uses hold-down timers to make the network more stable in case of a flapping link.

Response to Question 15:

Correct option is C.

Explanation: Complete routing table is send at periodic intervals by distance vectors. Whereas, link state updates the state of its own links to all the routers in the network.

Response to Question 16:

Correct option is B.

Explanation: To determine best path to remote network, IGRP uses bandwidth and line delay. Line delay is also known as cumulative interface delay.

Response to Question 17:

Correct option is D.

Explanation: Three different ways are there to configure same default route however, two are given in answer. The route is set to 0.0.0.0.0.0.0.0 mask at first and then the next hop is specified. Another method that can be used is that the mask can be set at 0.0.0.0.0.0.0.0 and then the exit interface can be used. Therefore, the ip default approach can be used at last.

Response to Question 18:

IPv4 is Internet Protocol version 4 that is used to connect devices in network. It uses 32-bit address that can address a total of 2^32 addresses. However, it is said that with the increase in the number of internet users the addresses will not remain unused as every device like computing devices, game consoles as well as smartphones need an IP address to connect to the internetwork. Whereas, IPv6 is Internet Protocol version 6 that is used to meet the demand of more IP addresses. It follows IPv4 and is regarded as the next generation internet protocol. It coexists with the old version of Internet Protocol. It allows the steady growth of Internet by increasing the number of hosts in the network. However, there are added advantages of using IPv6. They are:

• There will be no more Network Address Translation.
• The network addresses can be automatically configured.
• The header format is simple.
• Quality of service is high.
• Privacy support can authentication is built-in.
• Administration over the network becomes significantly easy.
• The network that uses the IPv6 address will have flexibility in choosing options and extensions.
• Efficiency of routing will be increased.
• Multicast routing will also become easy.

These features are not provided by IPv4. Therefore, the implementation of the IPv6 will be more efficient than IPv4.

Response to Question 19:

IPv6 is the sixth version of Internet Protocol and uses 128-bits. Therefore, the total number of addresses that IPv6 can address is 2^128 addresses that is close to 3.4*10^38 addresses. IPv6 provides many technical benefits along with providing large address space. The IPv6 addresses are represented by 8 group of 4 hexadecimal digits and the 8 groups are separated by using colons. The main features of IPv6 addressing schemes are:

• It uses packet- switched network for the communication of data packets.
• End-to-end data transmission is facilitated.
• Assigning of address to different devices can be done easily.
• The subnet size of IPv6 is standardized. The host portion of the address is fixed to 64-bits.

IPv6 can be implemented in the network with the help of packet header, representation of address, types of addresses and multicast addresses. IPv6 has 40 octets whereas IPv4 has 20 octets. IPv6 has few fields and the header is 64- bits that is significantly efficient. The header of IPv6 consists of version information, traffic class, address of the next header, payload length, hop limit, source address, destination address and header that is used for extension.

Response to Question 20:

There are many differences between the various broadband technologies that is present like ADSL, Fiber technologies and cellular technologies. ADSL is the abbreviation of Asymmetric digital subscriber line. The technology is used for fast communication of data in the internet. It is wired technology and uses copper cables to transmit data. Fiber technology uses optical fibers for transferring data within broadband internet. Cellular technology is the mobile technology that is used for communicating data in the internet. It is regarded as wireless broadband because the data communication process does not make use of wired network. The differences between the three technologies are given below:  

ADSL	Fiber technology	Mobile or cellular technology
Provides poor service to the users.	Provides moderate service to the users.	Provides great convenience to the users.
Data transmission rate is slow	Data transmission rate is the highest	Data transmission rate is high.
Does not provide any choice to the users	Provides 6 to 10 choices to the user.	Gives less choice to the user.
Do not require a particular platform for its access.	Should have a particular platform for its access.	Should have a particular platform for accessing cellular technology.

Task 2:

Exhibit:

The addressing schemes that is used in the network are B, C and F.

Explanation: The number of host that is present in VLAN 2 are 114. Therefore, to calculate the host address we need 7 zeroes in 8 bits. If 7 bits are 0 then 2^7-2=126 which is greater than 114. The IP addresses of each host that is Host A and Host B are in class B as the addresses are 172.16.1.126 and 172.16.1.129 respectively. The default classless inter-domain routing subnet mask of class B is /16. Therefore, the number of bits in use are 16-7 = 9 bits. The extra 1 bit is for the sub-network mask. From the above explanation, it is clear that the subnet mask will be 255.255.255.128. Therefore, the option B is correct.

The IP address 172.16.1.25 is the sub-network of VLAN 1 that can be assigned to the hosts of VLAN. The sub-network of VLAN is 172.16.1.0/25. Therefore, option C is correct.

To carryout communication between VLAN 1 and VLAN 2, router’s Local Area Network interface needs to be divided into multiple sub-interfaces that consists of multiple Internet Protocol addresses. Therefore, option F is true.

References:

Batra A, 'Internet Protocol Version 6 (Ipv6)' (2017) V International Journal for Research in Applied Science and Engineering Technology

Gao JQ Zhao, '6In4 Tunnel Based Ipv6 Transition Solution For Ipv4 Mobile Terminals' (2014) 3 International Journal of Computer and Communication Engineering