Computer Networks Questions & Answers – BGP

This set of Computer Networks Multiple Choice Questions & Answers (MCQs) focuses on “BGP”.

1. How many categories are present in the autonomous systems?
a) Stab and transit
b) Stub, transit and multi-homed
c) Multi-homed, stab and transit
d) Multi-homed and stub
View Answer

Answer: b
Explanation: Transit is the only AS that allows data traffic to go through it. Stub and multi-homed will have connections with single and multiple AS respectively and do not allow themselves to be a service provider to allow traffic across them.

2. Why a border gateway protocol (BGP) session is used in between routers?
a) To transmit the packets
b) To send the AS path
c) To interchange the routing information
d) To communicate with other AS
View Answer

Answer: c
Explanation: Usually BGP uses TCP services while establishing the sessions between BGP routers. A session is more like a connecting link to exchange only the information of routing and these BGP sessions are persistent.

3. Which type of BGP session can be established between 2 routers from different autonomous systems?
a) I-BGP session
b) E-BGP session
c) W-BGP session
d) O-BGP session
View Answer

Answer: b
Explanation: E-BGP stands for external border gateway protocol and internal BGP sessions are used only within the AS. Unlike I-BGP, external BGP sessions are used to share and retrieve the routing information of the routers which belongs to different AS.

4. What will happen if two networks choose the policy called peering in place of transit service that is given by a provider?
a) Reduced traffic
b) More transitive
c) Increase traffic
d) High bills
View Answer

Answer: a
Explanation: The traffic that autonomous systems get when they do peering is low compared to the traffic that they get when they use provider. And also, the provider lets its other customers to know the path of these ASs and it leads to more traffic to these ASs.

5. Why border gateway protocol is called as path vector protocol?
a) Router maintains table for each path
b) Router keeps track of the path
c) Router defines a path with prior knowledge
d) Router selects the shortest path
View Answer

Answer: b
Explanation: Basically, intra-domain routing maintains the table for each destination with least cost or distance. But in BGP, metric is policy, so every router keeps track of the path like next hop and AS path. This path vector protocol avoids looping using path tracking.
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6. When is it prominent to use border gateway protocol?
a) When AS is not aware of path selection
b) When routers have less capacity
c) When autonomous system is stab AS
d) when autonomous system is transit AS
View Answer

Answer: d
Explanation: Border gateway protocol is more useful when the AS is transit because BGP is capable of inter-domain routing. So, it can handle the data traffic well when the ASs are transit.

7. How a path can be defined in border gateway protocol?
a) List of routers
b) Sequence of autonomous systems
c) List of Attributes
d) List of routes
View Answer

Answer: c
Explanation: When traffic is sent from one network to another network, then every router within the route checks the path. This path contains not only the number of AS but also contains attributes that give information about the path such as next_hop.

8. What are the two broad categories of attributes of a path in border gateway protocol?
a) Transitive and non-transitive
b) Mandatory and discretionary
c) Well-known and optional
d) Mandatory and optional
View Answer

Answer: c
Explanation: Well known and optional are two major categories of attributes. Mandatory and discretionary are categories of well-known attribute. Optional attribute also has two categories called transitive and non-transitive.

9. Which of the following is not a well-known mandatory attribute of path in border gateway protocol?
a) Origin
b) As_path
c) Next-hop
d) Next_AS
View Answer

Answer: d
Explanation: Origin defines the source of the packet and As_path defines the sequence of ASs that a packet follows and Next_hop defines about the next router that a packet is going to visit.

10. Border gateway protocol is used within the Autonomous systems just like IGP protocols work.
a) True
b) False
View Answer

Answer: b
Explanation: IGP protocols are intra-domain protocols, whereas BGP is an inter-domain protocol. It works among the autonomous systems which are owned by individual administrations rather than working within the autonomous system.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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