CCNP BGP Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Router R1:

R1# show bgp ipv4 unicast 192.168.1.0/24
BGP routing table entry for 192.168.1.0/24, version 15
Paths: (1 available, best #1, table default)
  Advertised to update-groups:
     1
  Refresh Epoch 1
  65050, (received & used)
    10.0.1.2 from 10.0.1.2 (10.0.0.2)
      Origin IGP, metric 0, localpref 100, weight 0, valid, external, best
      rx pathid: 0, tx pathid: 0x0

Based on this output, what can be concluded?

Accepted Answer

The route is from AS 65050 and is the best path.. The output shows the BGP table entry for 192.168.1.0/24 with path 65050, and the line 'valid, external, best' confirms that this route is from AS 65050 and is selected as the best path. The 'best' keyword in the status flags directly indicates that this path is the best among all available paths for this prefix.

Answer

The route was learned from an internal BGP peer.

Answer

The route has a local preference of 0.

Answer

The route is not valid because it is external.

Question 2

A network engineer runs the following command on Router R1:

R1# show bgp ipv4 unicast neighbors 10.0.1.2
BGP neighbor is 10.0.1.2, remote AS 65050, external link
  BGP version 4, remote router ID 10.0.0.2
  BGP state = Established, up for 00:23:45
  Last read 00:00:15, last write 00:00:10, hold time is 90, keepalive interval is 30 seconds
  Neighbor sessions:
    1 active, is not multisession capable
  Neighbor capabilities:
    Route refresh: advertised and received(new)
    Four-octets ASN: advertised and received
    Address family IPv4 Unicast: advertised and received
    Enhanced Refresh: advertised and received
    Multisession: advertised
  Message statistics:
    InQ depth is 0
    OutQ depth is 0
                         Sent       Rcvd
    Opens:                  1          1
    Notifications:          0          0
    Updates:                5          3
    Keepalives:            47         48
    Route Refresh:          0          0
    Total:                 53         52
  Default minimum time between advertisement runs is 30 seconds

Based on this output, what can be concluded?

Accepted Answer

The BGP session is up and functioning normally.. Option C is correct because the BGP state is 'Established', the hold time (90 seconds) and keepalive interval (30 seconds) are standard, and the last read (15 seconds ago) and last write (10 seconds ago) are well within the hold time, indicating the session is stable and functioning normally. The InQ and OutQ depths are 0, confirming no queued updates or issues.

Answer

The BGP session is in the 'Idle' state because the last read was 15 seconds ago.

Answer

The neighbor is an internal BGP peer because the remote AS is 65050.

Answer

The neighbor has sent 5 updates and received 3 updates.

Question 3

A network engineer runs the following command on Router R1:

R1# show bgp ipv4 unicast 10.0.0.0/8
BGP routing table entry for 10.0.0.0/8, version 25
Paths: (2 available, best #2, table default)
  Advertised to update-groups:
     1
  Refresh Epoch 1
  65050 65100
    10.0.1.2 from 10.0.1.2 (10.0.0.2)
      Origin IGP, metric 0, localpref 100, weight 0, valid, external
      rx pathid: 0, tx pathid: 0x0
  65050
    10.0.1.3 from 10.0.1.3 (10.0.0.3)
      Origin IGP, metric 0, localpref 100, weight 0, valid, external, best
      rx pathid: 0, tx pathid: 0x0

Based on this output, what can be concluded?

Accepted Answer

Path #2 is the best path because it has a shorter AS_PATH.. BGP selects the best path based on a set of well-defined tie-breaking rules. After comparing weight, local preference, and origin, the next step is AS_PATH length. Path #2 has an AS_PATH of '65050' (one AS), while Path #1 has '65050 65100' (two ASes). Since a shorter AS_PATH is preferred, Path #2 is chosen as the best path, making option B correct.

Answer

Path #1 is the best path because it has a longer AS_PATH, indicating more specific routing.

Answer

Both paths are equally preferred, and BGP uses tie-breaking rules like router ID.

Answer

Path #2 is the best path because it is received from a higher IP address.

Question 4

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65001
 neighbor 10.0.0.2 route-map SET_COMMUNITY in
!
route-map SET_COMMUNITY permit 10
 set community 100:200
!
What is the effect of this configuration?

Accepted Answer

Routes received from 10.0.0.2 are tagged with community 100:200, but the community is not sent to other BGP peers unless send-community is configured.. The route-map SET_COMMUNITY is applied to inbound updates from neighbor 10.0.0.2, so routes received from that neighbor are tagged with community 100:200. However, BGP does not propagate communities to other peers unless the neighbor is explicitly configured with the send-community command. Without send-community, the community attribute is stripped from outbound updates, so the community is not sent to other BGP peers.

Answer

Routes received from 10.0.0.2 are tagged with community 100:200 and automatically sent to all neighbors.

Answer

The route-map is applied to outbound updates to 10.0.0.2, setting community on routes sent to that neighbor.

Answer

The configuration is invalid because the community must be a string, not a numeric value.

Question 5

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65000
!
Which statement about this configuration is true?

Accepted Answer

This is an iBGP session because the remote AS matches the local AS.. This configuration establishes an iBGP session because the local AS number (65000) matches the remote AS number (65000). In BGP, when both routers share the same AS, the session is classified as internal BGP (iBGP), regardless of the IP addressing scheme used.

Answer

This is an eBGP session because the neighbor IP is in a different subnet.

Answer

The router will automatically set next-hop-self for routes sent to this neighbor.

Answer

The configuration is invalid because iBGP requires a loopback interface.

Question 6

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65001
 neighbor 10.0.0.2 ebgp-multihop 2
 neighbor 10.0.0.2 update-source Loopback0
!
What is the purpose of the ebgp-multihop 2 command?

Accepted Answer

It allows the eBGP session to be established with a neighbor that is not directly connected, with a maximum of 2 hops.. The ebgp-multihop 2 command allows an eBGP session to be established between peers that are not directly connected at Layer 3. By setting the TTL to 2, it permits the BGP packets to traverse one intermediate router (hop) to reach the neighbor, which is necessary when using loopback interfaces for eBGP peering.

Answer

It sets the maximum number of prefixes that can be received from the neighbor to 2.

Answer

It limits the number of paths BGP can install for load balancing to 2.

Answer

It enables BGP multipath for eBGP with a hop count of 2.

Question 7

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65001
 neighbor 10.0.0.2 route-map FILTER in
!
route-map FILTER deny 10
 match ip address prefix-list BLOCKED
route-map FILTER permit 20
!
ip prefix-list BLOCKED seq 5 permit 10.0.0.0/8
!
What is the effect of this configuration?

Accepted Answer

All routes from neighbor 10.0.0.2 are accepted except those matching 10.0.0.0/8.. The route-map FILTER is applied inbound from neighbor 10.0.0.2. Sequence 10 denies routes that match the prefix-list BLOCKED, which permits 10.0.0.0/8. Sequence 20 is a permit statement with no match, which implicitly permits all other routes. Therefore, only routes matching 10.0.0.0/8 are denied, and all other routes are accepted.

Answer

Only routes matching 10.0.0.0/8 are accepted from the neighbor.

Answer

The configuration is invalid because route-map must have a permit statement first.

Answer

The prefix-list is misconfigured because it should use 'deny' instead of 'permit'.

Question 8

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65001
 neighbor 10.0.0.2 route-map SET_MED out
!
route-map SET_MED permit 10
 set metric 50
!
What is the effect of this configuration on routes advertised to 10.0.0.2?

Accepted Answer

All routes sent to 10.0.0.2 will have the MED value set to 50.. Option A is correct because the route-map SET_MED is applied to outbound updates to neighbor 10.0.0.2, and the 'set metric 50' command sets the Multi-Exit Discriminator (MED) attribute to 50 for all routes advertised to that neighbor. The MED is a metric used to influence inbound traffic from the AS of the neighbor, and it is propagated to the neighbor's BGP table.

Answer

Routes received from 10.0.0.2 will have their MED set to 50.

Answer

The local preference of routes sent to 10.0.0.2 is set to 50.

Answer

The configuration is invalid because MED cannot be set on outbound updates.

Question 9

router bgp 65000
 bgp router-id 10.0.0.1
 neighbor 10.0.0.2 remote-as 65001
 neighbor 10.0.0.2 route-map SET_ORIGIN in
!
route-map SET_ORIGIN permit 10
 set origin incomplete
!
What is the effect of this configuration?

Accepted Answer

Routes received from 10.0.0.2 will have their origin set to incomplete, making them less preferred compared to IGP origin.. The route-map SET_ORIGIN is applied as an inbound filter to neighbor 10.0.0.2. When a route is received, the 'set origin incomplete' command changes the origin attribute to incomplete (value 2). In BGP path selection, origin incomplete is the least preferred origin type, making these routes less preferred than routes with IGP (value 0) or EGP (value 1) origin.

Answer

Routes sent to 10.0.0.2 will have their origin set to incomplete.

Answer

The router will not advertise any routes with origin incomplete to other peers.

Answer

The configuration is invalid because origin cannot be changed with a route-map.

Question 10

What is the default value of the BGP 'weight' attribute for routes learned from a neighbor?

Accepted Answer

0. The BGP 'weight' attribute is a Cisco-proprietary attribute that is locally significant only to the router on which it is configured. By default, routes learned from a BGP neighbor have a weight of 0, while routes originated locally on the router (e.g., via network or aggregate-address commands) have a weight of 32768. Weight is the highest priority BGP attribute in the path selection process, so a route with a higher weight is preferred over one with a lower weight.

Answer

100

Answer

32768

Answer

1

Question 11

Which BGP attribute is used to indicate the degree of preference for a route within an AS and is propagated to all iBGP peers?

Accepted Answer

Local preference. Local preference is a well-known mandatory BGP attribute that indicates the degree of preference for a route within an AS. It is propagated to all iBGP peers and, by default, is set to 100. A higher local preference value is preferred when selecting the best path for outbound traffic from the AS.

Answer

MED

Answer

Weight

Answer

AS-path

Question 12

In BGP best path selection, which of the following is compared first?

Accepted Answer

Highest weight. BGP best path selection begins by comparing the weight attribute, which is Cisco-proprietary and local to the router. The path with the highest weight is preferred first, making option A correct. Weight is evaluated before any other BGP attribute, including local preference, AS-path length, and MED.

Answer

Highest local preference

Answer

Shortest AS-path

Answer

Lowest MED

Question 13

Drag and drop the steps of BGP session establishment between eBGP peers into the correct order, from first to last.

Accepted Answer

TCP SYN sent from active peer. BGP session establishment begins with the TCP three-way handshake (SYN, SYN-ACK, ACK). Once TCP is established, BGP sends an OPEN message to negotiate capabilities. The peer responds with an OPEN message. After both OPENs are exchanged, BGP sends KEEPALIVE messages. Finally, the session moves to the Established state and UPDATE messages can be exchanged.

Question 14

Drag and drop the steps of BGP best path selection process into the correct order, from first to last.

Accepted Answer

Prefer highest weight. BGP best path selection follows a strict order: first, prefer the path with the highest weight (Cisco proprietary). If equal, prefer highest local preference. Next, prefer locally originated routes (network/aggregate). Then, prefer the shortest AS_PATH. Finally, prefer the lowest MED (if same AS).

Question 15

Drag and drop the steps of configuring an iBGP route reflector cluster into the correct order, from first to last.

Accepted Answer

Enable BGP on route reflector. First, enable BGP on the route reflector. Second, configure the route reflector's cluster ID (if not using router-id). Third, configure the route reflector clients. Fourth, establish iBGP peerings between the route reflector and its clients. Finally, verify that the route reflector is advertising routes correctly.