BGP INTERVIEW QUESTIONS
HomeINTERVIEW QUESTIONSBGP INTERVIEW QUESTIONS
- Explain Split-Horizon, Synchronization rules.
- Which 2 new attributes are seen when we enable summarization in BGP?
- Why BGP specifically chooses neighbor method for creating sessions and why not the sessions are allowed to be configured dynamically as happen in IGPs(say EIGRP and OSPF).
- Two peers for iBGP neighborship on Loopback addresses while one of the peers doesn’t has update-source loopback x command missing. Explain why?
- Can we form eBGP neighborship b/w two peers where one peer take physical interface address of remote-peer and 2nd peer taking loopback address of remote-peer. Yes or No, with explanation.
- Explain BGP TTL Security concept with an example.
- What is use of neighbor x.x.x.x local-as y command?
- How can you prevent your BGP AS becoming a Transit-AS. Explain various methods.
- Under one of Route-Reflector rules, a route advertised from a non client is not advertised to another non-client. Explain why.
- When is command “remove private-as” in BGP used.
- What are terms route-servers and looking-glass?
- What 2 new attributes are seen when we configure a route-reflector in the topology.
- Explain route-refresh capability in BGP and its use.
- What is difference b/w the output of commands “show ip bgp neighbor x.x.x.x routes” and “show ip bgp neighbor x.x.x.x received-routes”.
- A bgp peer’s neighborship getting reset every 3 mins(or say on hold time expiry). Explain the reason and the solution.
- Explain the difference b/w standard communities “no-export”, and “local-as”.
- The router advertises a prefix to its peer even when it is marked with the community “no-advertise” using command neighbor x.x.x.x route-map COMM out. Explain why?
- Name few BGP process names seen in “show process cpu”.
- What are the 3 well-known mandatory attributes?
- Explain the meaning of “next-hop-self”keyword and when it is used in BGP?
- Explain BGP MRAI timer. What are its default values?
- What is default Weight of remote prefix on a router?
- Can we set local-preference in an outward direction to a peer? if yes, how?
- What is use of “as-set” keyword in BGP route aggregation.
- Explain the meaning for “rib-failure”? Where and when is this seen?
- A route is present in the BGP table but not getting exported to routing table. Explain the possible reasons.
- Explain various methods of load balancing in BGP.
- Explain BGP Backdoor concept.
- What is default metric when a RIP, EIGRP, OSPF, or an ISIS route is redistributed into BGP?
- What transport protocol is used for BGP?
- What is the origin-as for a prefix with the AS-Path 200 500 100 450?
- Can we configure “update-source loopback x” command with eBGP peers?
- Why we have to use ebgp-multihop x command for non directly connected eBGP peers?
- How can we generate a label for a prefix using BGP?
- Say on Router R1, there is a BGP configuration “neighbor x.x.x.x route-map XYZ out”, and the route-map “XYZ” doesn’t exist. Will router R1 be able to communicate/send updates to peer x.x.x.x?
- Under the above scenerio again, now say that we have the route-map “XYZ” but there are no rules under it and it is an empty route-map. Will router R1 be able to communicate/send updates to peer x.x.x.x now ? What is the solution to above two problems?
- How would you match an existing community attribute say “100:100” on a BGP router and add an additional BGP community 200:200 to it?
- One of the route-reflector rules say that a route learned by an RR from a non client is not advertised to another non clients but only to its clients. Explain why?
- What are BGP “attribute-map” and “suppress-map” terms? When are these used?
- Explain the attribute “Aggregate-address”. What is its function?
- What is use of “as-set” keyword in BGP route-aggregation?
- You have set a community “no-advertise” for a prefix in out direction to a peer. The prefix is still advertised to the peer. Why? How can you solve this?
- What are as-path access-lists? When are these used?
- What is BGP route-dampening?
- We are able to ping the BGP peer but not able to establish BGP session. What are the possible reasons?
- Can you form an eBGP session b/w two peers, where peer A is using peer B’s loopback address to create session and peer B is using peer A’s physical interface address?
- Can BGP generate labels? Explain how?
- What are BGP peer-groups? What is its use?
- Explain BGP states.
- Explain the fields of BGP “OPEN” message?
- Do BGP messages have any header? What is minimum length of the header?