Most Commonly Asked BGP
Interview Questions
Ø
How does IP RIB
Update allocate memory?
Ø
What is the BGP AD
value?
Ø
How can I filter all
IP routes advertised to a BGP neighbour except the default route 0.0.0.0/0?
Ø
Is it possible to
track an interface and change the route availability?
Ø
What is the command
to see IPv6 BGP neighbours?
Ø
In regards to the
removal of the static route “ip route 10.10.0.0 255.255.0.0 Null0”, does no
auto-summary in BGP cause all subnets of 10.10.0.0 to be advertised?
Ø
Why are there no
statistic results when I use the debug bfd events and debug bfd packets
commands?
Ø
What do you mean by
split-horizon in the context of BGP?
Ø
What are the many
sorts of Timers available in BGP?
Ø
What are the
different BGP Path Attributes?
Ø
Describe the BGP
path selection criteria?
Ø
What is the best way
to configure BGP with a loopback address?
Ø
Can I run two BGP
process on a single router?
Ø
Difference between
hard reset and soft reset in BGP?
Ø
What are different
BGP message types
Ø
What are various BGP
states?
Ø
What are the
benefits of configuring BGP peer groups?
Ø
What is the default
BGP ConnectRetry timer
Ø
What does r
RIB-Failure mean in the show ip bgp command output?
Ø
How can I filter all
IP routes advertised to a BGP neighbour except the default route 0.0.0.0/0?
Ø
What is the version
of BGP that first supported CIDR?
Ø
In the global
routing table, can the same AS number shows up more than once in a path?
Ø
Can I run two BGP
process on a single router?
Ø
What is the cost of
external and internal BGP routes?
Ø
Which parameters and
attributes have to be equal before MED is compared to select the best path?
Ø
How do we enable
community propagation?
Ø
What is the purpose
of route dampening?
Ø
In general which
routes will affect by route dampening? eBGP or iBGP?
Ø
What is the default
value of MED?
Ø
Can router on
different subnet become BGP neighbour?
Ø
What is the
difference between eBGP multihop and TTL security?
Ø
Which protocol and
the port number does BGP use for neighborship?
Ø
How do I configure
BGP?
Ø
What is the use of
BGP best path community ignore command?
Ø
How do I configure
BGP with the use of a loopback address?
Ø
What is the order of
preference of attributes when applied to one neighbour in BGP?
Ø
What does a next-hop
of 0.0.0.0 mean in the show IP BGP command output?
Ø
What are the
well-known communities of the BGP community attribute?
Ø
How does BGP behave
differently with auto-summary enabled or disabled?
Ø
What formats can I
use to configure the BGP community attribute?
Ø
When and how should
I reset a BGP session?
Ø
Is there any special
configuration needed on PIX/ASA to allow BGP sessions through it?
Ø
What is an
autonomous system number (ASN) and how do I obtain one?
Ø
What is the BGP path
selection criteria?
Ø
What is the
difference between always-compare-med and deterministic-med?
Ø
Do internal BGP
(iBGP) sessions modify the next-hop?
Ø
Do external BGP
(eBGP) sessions modify the next-hop?
Ø
Do external BGP
(eBGP) sessions between confederations modify the next-hop?
Ø
In external BGP
(eBGP) sessions, which IP address is sent as the next hop?
Ø
Does the route
reflector change the next-hop attribute of a reflected prefix?
Ø
How can I announce a
prefix conditionally to one ISP only when I lose the connection to my primary
ISP?
Ø
How can I configure
BGP to provide load sharing and redundancy in my network?
Ø
How much memory
should I have in my router to receive the complete BGP routing table from my
ISP?
Ø
What are the
benefits of configuring BGP peer groups?
Ø
Why do I see the
same route twice from the same peer in BGP?
Ø
What is
synchronization, and how does it influence BGP routes installed in the IP
routing table?
Ø
How do I know which
Cisco IOS software release supports a particular BGP feature?
Ø
How can I set the
Multi Exit Discriminator (MED) value on prefixes advertised to external BGP
(eBGP) neighbours to match the Interior Gateway Protocol (IGP) next hop metric?
Ø
What is the default
BGP ConnectRetry timer, and is it possible to tune the BGP ConnectRetry timer?
Ø
What does r
RIB-Failure mean in the show ip bgp command output?
Ø
How can I
redistribute internal BGP (iBGP) learned default-route (0.0.0.0/0) route into
EIGRP/OSPF/IS-IS?
Ø
Which command is
used to disable BGP neighborship?
Ø
What are the values
of keepalive and Dead timers in BGP?
Ø
How many public and
private AS numbers are there?
Ø
BGP Route selection
criteria?
Ø
Does the router have
to be restarted after a new BGP Neighbor Maximum Prefix is configured?
Ø
Is there a command
to check the advertised routes along with the prepend of the AS-paths?
Ø
How does neighbour
soft-reconfiguration inbound command function?
Ø
What is the
difference between when a route is injected in BGP via redistributing command
or a network command?
Ø
How do I verify
Layer 4 forwarding summary information?
Ø
What are IGPs and
EGPs and why are they different?
Ø
Name several path
attributes and their function.
Ø
Why is there a
problem with iBGP in large networks? How can this problem be solved?
Ø
Name BGP path
attributes to control incoming and outgoing traffic
Ø
My BGP is showing
0.0.0.0 as router-id; what could be the possible reason?
Ø
If my BGP neighbour
is stuck in an idle or active state, what should I do?
Ø
Explain BGP
recursive lookup and site of origin (SoO).
Ø
What do you
understand by BGP split-horizon rule?
Ø
Describe BGP
communities. Name well-known communities.
Ø
Can I use BGP
instead of any IGP?
Ø
Types of a BGP
routing table?
Ø
What is route
reflector and why it is required?
Ø
What is
no-synchronization rule?
Ø
What are Default BGP
timers?
Ø
In Multihoming
scenario, if the primary link gets fail, after how long traffic will be shifted
to the secondary link?
Ø
BGP Graceful
Restart, NSR and NSF?
Ø
How to use BGP as
PE-CE backdoor link?
Ø
What is the
advantage of using BGP AS Prepend?
Ø
What is cluster id
in BGP?
Ø
What is the meaning
of update-source loopback?
Ø
Can we use local
preference outside the autonomous system?
Ø
What is
confederation?
Ø
What is Route
Reflector in BGP? Why is it required?
Ø
What will the BGP
first check to see if a prefix is accessible?
Ø
What are the two
methods for reducing the number of IBGP connection in a network?
Ø
What makes a
neighbour internal BGP (iBGP)?
Ø
What the command
“neighbour update-source” do?
Ø
Explain the term RIB
in BGP?
Ø
Two BGP peers
connected through a routed firewall are unable to establish a peering
relationship. What could be the most likely cause?
Ø
What is the order of
preference of attributes (route-map, filter-list,prefix-list, distribute-list )
when some or all are applied to one neighbour in BGP? Kindly share for inbound
updates?
Ø
What is the order of
preference of attributes (route-map, filter-list,prefix-list, distribute-list )
when some or all are applied to one neighbour in BGP? Kindly share for inbound
updates?
Ø
How can I verify if
a BGP router announces its BGP networks and propagates them?
Ø
What is the
difference between always-compare-med and deterministic-med?
Ø
Does the route
reflector change the next-hop attribute of a reflected prefix?
Ø
How can I announce a
prefix conditionally to one ISP only when I lose the connection to my primary
ISP?
Ø
How much of minimal
RAM is required to learn complete BGP routing table from one BGP peer?
