RIP- Part 3 - BASIC INTERVIEW QUESTION

Question - 1 Which category is RIP belong to ?

RIP is a standard based, Distance Vector, Interior Gateway Protocol (IGP) used by router to exchange the routing information.

Question - 2 Why is RIP known as Distance Vector?

RIP is known as Routing Information Protocol an it is a Distance Vector because it uses hop count to determine the best path to remote network. It has two version 1 (Classful) and version 2 ( Classless).

Question - 3 What is administrative distance of RIP ?

Administrative distance of RIP is 120

Question - 4 Which metric is used by RIP ? 

Only Hop Count metric is used by RIP.

Question - 5 What is the limit of hop count in RIP ?

Limit of hop count in RIP is 15, means if anything require 16 hop, it will be deemed unreachable.

Question - 6 How is RIP select the best path to the remote network ?

RIP only uses hop count to determine the best path to the remote network, route with  lowest hop count will be prefer as best path to remote network. If RIP finds more than one link with the same hop count to the same remote network, it will automatically perform a Round-Robin load balancing. RIP can perform load balancing for up to 6 equal cost link and by default is 4.

Question - 7 Why RIP causes overhead in network?

Routers which are configured with RIP, periodically exchange all of its routing table information with others in every 30 seconds. So if assuming a scenario has 100 RIP networks in one router and there are 15 routers , so there would be 15 routers exchanging the information with each other even if its same info. Therefore, it causes overhead. If its RIPv1- then it will broadcast so every other router will hear the info. For RIPv2 its multicast.

Question - 8 Which transport layer protocol used by RIP ?

RIP use UDP (User Datagram Protocol) as one of its Transport protocol, and assigned the reserved port number 520.

Question - 9 Which algorithm used by RIP ?

RIP uses Bellman Ford algorithm.

Question - 10 Why RIP is inefficient on large network ?

RIP is inefficient on large networks with slow wan link or on network with large number of router installed.

Question - 11 Explain RIP process.

In a RIP network, each router broadcast its entire routing table to its all neighboring routers or on all active interfaces after every 30 second. After that, when a router receives a neighbor's routing table, it uses these provided information to update its own routing table and then sends own updated routing table to its all neighbors.

Question - 12 Explain load balancing in RIP.

If there are more than one link available with the same hop count to the same destination in RIP network, then RIP will perform a Round-Robin load balancing automatically. RIP can perform load balancing for up to 6 equal cost link and by default is 4.

Question - 13 What is the range of load balancing in RIP ?

Range of load balancing in RIP is 4 by default, but RIP can perform load balancing for up to 6 equal cost link.

Question - 14 What is differences between RIPv1 and RIPv2 ?

RIPv1 (Routing Information Protocol Version 1)

• It is Distance Vector Protocol.
• Interior Gateway Protocol.
• Maximum hop count limit is 15
• It is classful
• Broadcast Based
• Does not support VLSM (Variable Length Subnet Masking).
• There is no authentication.
• Does not support for Discontiguous Network
• Hello/Dead time - 30/180
• Broadcast based - RIPv1 sends routing update periodically every 30second as broadcast using destination IP address as limited broadcast IP address 255.255.255.255. Since the updates are sent using the destination IP address of limited broadcast IP address 255.255.255.255, every router need to process the routing update message (Whether they are running RIPv1 or not) 

RIPv2 (Routing Information Protocol Version 2)

• It is Distance Vector Protocol.
• Interior Gateway Protocol.
• Maximum hop count limit is 15
• It is classless
• Use multicast 224.0.0.9
• Support VLSM (Variable Length Subnet Masking).
• Allow for MD5 authentication.
• Support for Discontiguous Network
• Hello/Dead time - 30/180
• RIPv2 routing updates are sent as multicast traffic at destination multicast address of 224.0.0.9. Multicast updates reduces the network traffic. The multicast routing updates also helps in reducing routing update message processing overhead in routers which are not running RIPv2. Only the routers running RIPv2 join to the multicast group 224.0.0.9. Other routers which are not running RIPv2 can simply filter the routing update packet at layer 2

Question - 15 What is pinhole congestion ?

When two routes for the same destination have the same hop count in the RIP, this situation is known as Pinhole Congestion.

Question - 16 What is passive interface in RIP ?

This command prevents RIP update broadcasts from being sent out a specified interface, yet that same interface can still receive RIP updates. Thus a RIP router with a passive interface will still learn about the network advertise by other router.

Question -17 How to configure passive interface in RIP on particular interface ?

Router#config t
Router(config)#router rip
Router(config-router)#network 192.168.20.0
Router(config-router)#passive-interface serial 0/0

Question - 18 How to configure passive interface in RIP on all interface ?

We can configure all interfaces by using "passive-interface default" command and then individually ues the "no passive-interface" command on the interfaces we want updates to be sent out
Router#config t
Router(config)#router rip
Router(config-router)#network 192.168.20.0
Router(config-router)#network 192.168.30.0
Router(config-router)#passive-interface default
Router(config-router)#no passive-interface F0/0

Question - 19 How to configure passive interface in RIP when we used the neighbor command under the RIP process ?

If you used the neighbor command under the RIP process, the router will send unicast updates as well as multicast updates. The passive interface command must be used disable Multicast/broadcast updates and allowing only unicast.

Router#config t

Router(config)#router rip

Router(config-router)#passive-interface S0/0/0

Router(config-router)#passive-interface S0/1/0

Router(config-router)#neighbor 192.168.20.1

Router(config-router)#neighbor 192.168.30.1

Question - 20 Explain RIP timers ?

RIP uses four different type of timers.

Route update timer (30 Second) 

• Sets the interval (typically 30 seconds) between periodic routing updates in which the router sends a complete copy of its routing table out to all neighbors.

Route invalid timer (180 Second) 

• Determines the length of time that must elapse (180 seconds) before a router determines that a route has become invalid.If it hasn’t heard any updates about a particular route for that period. 
• When that happens, the router will send out updates to all its neighbors letting them know that the route is invalid.

Holddown timer (180 Second)

• This sets the amount of time during which routing information is suppressed. 
• Routes will enter into the holddown state 

1. when an update packet is received that indicates the route is unreachable. 
2. This continues either until an update packet is received with a better metric, the original route comes back up, or the holddown timer expires. 

• The default is 180 seconds.

Route flush timer (240 Second) 

• Sets the time between a route becoming invalid and its removal from the routing table (240 seconds). 
• Before it’s removed from the table, the router notifies its neighbors of that route’s impending demise. 
• The value of the route invalid timer must be less than that of the route flush timer. 
• This gives the router enough time to tell its neighbors about the invalid route before the local routing table is updated.

Other Posts:-

OSI LAYERS AND FUNCTIONS
IP ROUTING BASIC
IP ROUTING SCENARIOS
RIP BASIC
RIP TROUBLESHOOTING
NETWORK COMMAND ISSUE
INTERFACE ISSUE
VERSION MISMATCH ISSUE
PASSIVE INTERFACE ISSUE
MAXIMUM HOP COUNT ISSUE
RIP OFFSET LIST CONFIGURATION
BGP - INTERVIEW QUESTIONS (Part - 1)
LAYER-2 SWITCHING

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Anubhav Upadhyay

Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.

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