CCNA Bgp Questions

Drag & Drophard

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

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

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).

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Drag & Dropmedium

Drag and drop the steps of BGP graceful restart negotiation steps into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Graceful restart begins with the restarting router sending an OPEN message with the graceful restart capability, followed by the peer acknowledging, then the restarting router marking routes as stale, and finally the peer sending End-of-RIB markers.

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MCQhard

A network engineer is troubleshooting a BGP issue where a router is not installing a specific prefix in its routing table, even though the prefix is present in the BGP table. The engineer runs 'show ip bgp 10.0.0.0/24' and sees that the route is valid but not best. The BGP table shows that the route has a higher local preference than the current best path, but the AS_PATH is longer. What is the most likely reason the route is not being selected as best?

A.The route with higher local preference has a lower weight than the current best path.

B.The route with higher local preference has a higher MED value.

C.The route with higher local preference is not synchronized with IGP.

D.The route with higher local preference was learned from an eBGP peer, while the current best path is from an iBGP peer.

AnswerA

Correct because weight is checked before local preference in BGP path selection; a higher weight on the current best path would make it preferred even if local preference is lower.

Why this answer

BGP selects the best path based on a sequence of comparison steps. Local preference is checked before AS_PATH length, so a higher local preference should normally win. However, weight is the very first criterion in the BGP best-path selection algorithm.

If the current best path has a higher weight than the route with higher local preference, weight overrides local preference, making the higher-local-preference route not best.

Exam trap

Cisco often tests the order of BGP best-path selection steps, specifically that weight is evaluated before local preference, leading candidates to incorrectly assume that a higher local preference always wins regardless of weight.

How to eliminate wrong answers

Option B is wrong because MED is compared only after the AS_PATH length and origin code, and it is not relevant when a higher local preference is present; the issue here is that weight, which is checked first, is higher on the current best path. Option C is wrong because BGP synchronization is a Cisco-specific feature that requires an IGP route for the next-hop before installing an iBGP route, but it does not affect the best-path selection process; the route is already in the BGP table as valid, and synchronization would prevent installation, not selection as best. Option D is wrong because eBGP routes are preferred over iBGP routes only if all earlier steps (weight, local preference, locally originated) are equal; here, local preference is higher on the candidate route, but weight is the first tiebreaker and is higher on the current best path, so the eBGP vs iBGP comparison never occurs.

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Matchingmedium

Drag and drop each BGP attribute on the left to its preferred value (highest or lowest) on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Highest

Lowest

Why these pairings

Higher WEIGHT and LOCAL_PREF are preferred; lower MED, AS_PATH length, and IGP metric to next-hop are preferred.

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Drag & Dropmedium

Drag and drop the steps of BGP route aggregation and suppress-map process into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

First, you define the prefix-list to match specific routes. Then you create the route-map with the suppress clause. Next, you configure the aggregate-address command referencing the route-map.

After that, you verify the aggregated route in the BGP table. Finally, you check that more specific routes are suppressed.

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Multi-Selectmedium

Which three statements about BGP peering are true? (Choose three.)

Select 3 answers

A.eBGP peers are typically directly connected, but can be multi-hop with the ebgp-multihop command.

B.iBGP peers can be non-directly connected and often use loopback interfaces for reachability.

C.The default TTL for eBGP packets is 255.

D.In iBGP, all routers within the same AS must be fully meshed unless route reflectors or confederations are used.

E.The BGP router ID is used only for OSPF, not for BGP.

AnswersA, B, D

Correct because eBGP by default assumes direct connection, but multi-hop is possible.

Why this answer

eBGP peers typically use a directly connected interface or a loopback with proper routing. iBGP peers can be non-directly connected and often use loopback interfaces for stability. The TTL for eBGP is set to 1 by default, but can be increased with the ebgp-multihop command. iBGP requires that all routers in the same AS are fully meshed or use route reflectors to avoid loops. The BGP identifier (router ID) is used to identify the BGP speaker and is used in loop prevention for iBGP.

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Multi-Selecthard

Which three statements about BGP route selection are true? (Choose three.)

Select 3 answers

A.A route with a lower MED is preferred over a route with a higher MED when all other factors are equal.

B.A route with a higher LOCAL_PREF is preferred over a route with a lower LOCAL_PREF.

C.A route with a shorter AS_PATH is preferred over a route with a longer AS_PATH.

D.A route with a lower weight is preferred over a route with a higher weight.

E.A route with ORIGIN code EGP is preferred over a route with ORIGIN code IGP.

AnswersA, B, C

Correct: MED is used to influence inbound traffic; a lower MED is preferred.

Why this answer

The BGP best-path selection algorithm considers the highest weight first, then highest LOCAL_PREF, then locally originated routes (network or aggregate), then shortest AS_PATH, then lowest ORIGIN code (IGP < EGP < incomplete), then lowest MED, and so on. Routes with a lower MED are preferred. The highest LOCAL_PREF is preferred.

The shortest AS_PATH is preferred. The lowest ORIGIN code is preferred. The lowest weight is not preferred; weight is Cisco-specific and higher weight is preferred.

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Drag & Dropmedium

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

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

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.

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Matchingmedium

Drag and drop each BGP message type on the left to its matching function on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Establishes BGP peering parameters

Advertises or withdraws prefixes

Reports error conditions

Maintains session liveness

Requests re-advertisement of routes

Why these pairings

OPEN establishes peering; UPDATE advertises/withdraws routes; NOTIFICATION signals errors; KEEPALIVE maintains session; ROUTE-REFRESH requests re-advertisement.

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Multi-Selectmedium

Which two statements about BGP path attributes are true? (Choose two.)

Select 2 answers

A.AS_PATH is a well-known mandatory attribute.

B.LOCAL_PREF is a well-known discretionary attribute.

C.MED is an optional transitive attribute.

D.ORIGIN is a well-known discretionary attribute used for loop prevention.

E.NEXT_HOP is an optional non-transitive attribute.

AnswersA, B

Correct: AS_PATH is well-known mandatory; it is always included in BGP updates and is used for loop prevention and path selection.

Why this answer

The AS_PATH attribute is well-known mandatory and is used for loop prevention and path selection. The LOCAL_PREF attribute is well-known discretionary and is used to influence outbound traffic from an AS. The MED attribute is optional non-transitive and is used to influence inbound traffic.

The ORIGIN attribute is well-known mandatory but not used for loop prevention. The NEXT_HOP attribute is well-known mandatory but is not optional.

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Drag & Dropmedium

Drag and drop the steps of BGP confederations setup between sub-ASes into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

First, you assign the confederation identifier (main AS). Then you define the member sub-AS numbers. Next, you configure eBGP peering between sub-ASes using the sub-AS numbers.

After that, you ensure iBGP is configured within each sub-AS. Finally, you verify confederation peers with show ip bgp neighbors.

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Matchinghard

Drag and drop each BGP path selection criterion on the left to its order of preference (1 = highest priority) on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Why these pairings

Weight (highest) is checked first, then LOCAL_PREF (highest), then locally originated routes, then AS_PATH (shortest), then ORIGIN (IGP < EGP < incomplete).

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Matchingmedium

Drag and drop each BGP attribute on the left to its matching attribute type on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Well-known mandatory

Well-known discretionary

Optional transitive

Optional non-transitive

Well-known mandatory

Why these pairings

AS_PATH is well-known mandatory; LOCAL_PREF is well-known discretionary; COMMUNITY is optional transitive; MULTI_EXIT_DISC is optional non-transitive; ORIGIN is well-known mandatory.

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Matchingmedium

Drag and drop each BGP message type on the left to its matching function on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Establishes a BGP session and negotiates capabilities

Advertises new routes or withdraws previously advertised routes

Reports an error condition and closes the BGP session

Periodically sent to keep the BGP session alive

Requests that a peer readvertise its routes

Why these pairings

OPEN establishes a BGP session; UPDATE advertises or withdraws routes; NOTIFICATION indicates an error; KEEPALIVE maintains the session; ROUTE-REFRESH requests readvertisement of routes.

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MCQeasy

A network engineer runs the following command on Router R1: R1# show bgp ipv4 unicast summary | include 10.0.1.5 10.0.1.5 4 65005 3456 3457 15 0 0 00:15:22 5 Based on this output, what can be concluded?

A.The BGP session with 10.0.1.5 has been down for 15 minutes and 22 seconds.

B.The BGP session with 10.0.1.5 is up and has received 5 prefixes.

C.The BGP session with 10.0.1.5 is in the 'Active' state.

D.The BGP session with 10.0.1.5 has sent 5 prefixes.

AnswerB

The number 5 in the State/PfxRcd column indicates 5 prefixes received, and the lack of a state word means the session is established.

Why this answer

The 'show bgp ipv4 unicast summary' output displays BGP neighbor status. The column 'Up/Down' shows '00:15:22', indicating the session has been established for 15 minutes and 22 seconds, not down. The last column shows '5', which under the 'PfxRcd' (Prefixes Received) column indicates the number of prefixes received from the neighbor.

Therefore, the session is up and has received 5 prefixes.

Exam trap

Cisco often tests the misinterpretation of the 'Up/Down' column, where candidates mistakenly read it as downtime instead of uptime, and the confusion between prefixes received (PfxRcd) and prefixes sent (PfxSent), which is not shown in this output.

How to eliminate wrong answers

Option A is wrong because the 'Up/Down' column value '00:15:22' represents the duration the session has been up, not down; a down session would show a different state or 'never'. Option C is wrong because the output shows a valid neighbor IP, AS number, and uptime, indicating the session is in the Established state, not Active; the Active state would not show prefixes received. Option D is wrong because the '5' in the output corresponds to prefixes received (PfxRcd), not sent; sent prefixes are not displayed in this summary output.

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Drag & Dropmedium

Drag and drop the steps of BGP policy application (route-map, prefix-list, AS-path ACL) into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

First, you create the prefix-list or AS-path ACL to match routes. Then you define the route-map with match and set clauses. Next, you apply the route-map to a neighbor under the BGP address-family.

After that, you clear the BGP session to apply the policy. Finally, you verify the policy effect with show ip bgp.

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Matchinghard

Drag and drop each BGP path selection criterion on the left to its correct order of preference (1 = highest priority) on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Why these pairings

Weight (highest) is checked first, then LOCAL_PREF (highest), then locally originated routes, then AS_PATH length (shortest), then ORIGIN (IGP > EGP > incomplete).

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Multi-Selecthard

Which two statements about BGP route selection are true? (Choose two.)

Select 2 answers

A.A route with a higher LOCAL_PREF is preferred over a route with a lower LOCAL_PREF.

B.A route learned via eBGP is preferred over a route learned via iBGP, all else being equal.

C.A route with a longer AS_PATH is preferred over a route with a shorter AS_PATH.

D.The MED attribute is always compared regardless of the AS of the neighbor.

E.The IGP metric to the next hop is the first criterion in BGP path selection.

AnswersA, B

Correct because BGP prefers higher local preference.

Why this answer

BGP prefers a route with a higher LOCAL_PREF (local preference) over a lower one. A route learned via eBGP is preferred over iBGP because eBGP routes have a lower administrative distance in the BGP decision process (step 7: prefer eBGP over iBGP). The MED is compared only if the routes are from the same neighboring AS.

The shortest AS_PATH is preferred, not the longest. The IGP metric to the next hop is compared only after many other steps.

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Multi-Selecthard

Which three statements about BGP route reflectors are true? (Choose three.)

Select 4 answers

A.Route reflectors reduce the number of required iBGP sessions in an AS.

B.A route reflector client must be fully meshed with all other clients.

C.The route reflector does not modify the AS_PATH or NEXT_HOP attributes when reflecting routes.

D.The ORIGINATOR_ID attribute is used to prevent routing loops in a route reflector environment.

E.Non-client peers of a route reflector must be fully meshed with each other.

AnswersA, C, D, E

Correct because route reflectors allow a hub-and-spoke topology, reducing sessions.

Why this answer

Route reflectors allow iBGP to scale by reducing the number of iBGP sessions. A route reflector client only needs to peer with the route reflector. The route reflector does not modify the AS_PATH or NEXT_HOP attributes.

The route reflector uses the ORIGINATOR_ID and CLUSTER_LIST attributes for loop prevention. A non-client peer must be fully meshed with other non-client peers.

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Multi-Selecthard

Which three statements about BGP route reflectors are true? (Choose three.)

Select 3 answers

A.Route reflectors allow iBGP speakers to advertise routes learned from other iBGP speakers without requiring a full mesh.

B.A route reflector client must be fully meshed with all other clients in the same cluster.

C.The route reflector can be a client of another route reflector.

D.The cluster ID is used to prevent routing loops in a route reflector environment.

E.The route reflector modifies the AS_PATH attribute to prevent loops.

AnswersA, C, D

Correct: This is the primary purpose of route reflectors; they relax the full mesh requirement.

Why this answer

Route reflectors are used to reduce the number of iBGP peers in an AS. They allow iBGP speakers to advertise routes learned from other iBGP speakers without requiring a full mesh. A route reflector client does not need to be fully meshed with other clients; it only peers with the route reflector.

The route reflector can be a client itself. The cluster ID is used to identify a route reflector cluster and to prevent loops. The route reflector does not modify the AS_PATH or NEXT_HOP attributes by default.

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MCQmedium

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?

A.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.

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

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

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

AnswerA

Correct. The route-map sets the community on inbound updates, but without send-community, the community is not propagated.

Why this answer

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.

Exam trap

Cisco often tests the distinction between inbound and outbound route-map application, and the fact that communities are not automatically sent to peers without explicit send-community configuration, leading candidates to assume the community is propagated by default.

How to eliminate wrong answers

Option B is wrong because BGP does not automatically send communities to all neighbors; the send-community command is required under the neighbor configuration for the community attribute to be included in outbound updates. Option C is wrong because the route-map is applied with the 'in' keyword, meaning it affects inbound routes from 10.0.0.2, not outbound updates to that neighbor. Option D is wrong because the community value 100:200 is a valid numeric format (AS:value) and is perfectly acceptable in BGP configuration.

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MCQhard

An enterprise has two BGP routers, R1 and R2, both in AS 65000. R1 peers with ISP1 (AS 100) and R2 peers with ISP2 (AS 200). The enterprise advertises a prefix 192.168.0.0/24 to both ISPs. The engineer wants to ensure that traffic from the Internet to this prefix enters the network primarily via R1, and only uses R2 if the link to ISP1 fails. Which BGP attribute should be manipulated on the updates sent to the ISPs?

A.Prepend AS 65000 multiple times on R2's updates to ISP2.

B.Set a higher MED on R1's updates to ISP1.

C.Set a higher local preference on R1 for routes learned from ISP1.

D.Use the no-export community on R1's updates to ISP1.

AnswerA

Correct because AS_PATH prepending makes the path through R2 longer, so ISP2 will prefer the path through ISP1, directing traffic to R1.

Why this answer

To influence inbound traffic from the Internet, you must manipulate attributes sent to the ISPs. AS path prepending makes a route appear less preferred by artificially lengthening the AS path. By prepending AS 65000 multiple times on R2's updates to ISP2, ISP2 will see a longer AS path for the prefix and prefer the shorter path via ISP1, causing traffic to enter primarily via R1 unless the ISP1 link fails.

Exam trap

Cisco often tests the distinction between attributes that influence inbound vs. outbound traffic; the trap here is confusing local preference (outbound) with AS path prepending (inbound), leading candidates to incorrectly choose local preference manipulation.

How to eliminate wrong answers

Option B is wrong because MED is a metric exchanged between ASes to influence inbound traffic from a neighboring AS, but it is only compared when paths come from the same neighboring AS; here ISP1 and ISP2 are different ASes, so MED would not be compared. Option C is wrong because local preference is an attribute used within an AS to influence outbound traffic, not sent to external peers; setting it on R1 for routes learned from ISP1 affects R1's choice of exit path, not how ISPs send traffic inbound. Option D is wrong because the no-export community prevents a route from being advertised to any eBGP peers beyond the immediate neighbor; using it on R1's updates to ISP1 would block the prefix from being propagated further, which is unrelated to influencing inbound path preference.

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MCQmedium

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?

A.All routes sent to 10.0.0.2 will have the MED value set to 50.

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

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

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

AnswerA

Correct. The route-map sets MED on outbound updates.

Why this answer

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.

Exam trap

Cisco often tests the distinction between outbound and inbound route-map application, and the trap here is confusing the 'set metric' command (which sets MED) with 'set local-preference' or assuming that MED cannot be set on outbound updates.

How to eliminate wrong answers

Option B is wrong because the route-map is applied to outbound updates ('out'), not inbound updates, so it does not affect routes received from 10.0.0.2. Option C is wrong because the 'set metric' command sets the MED, not the local preference; local preference is set using 'set local-preference' and is used for outbound traffic within the local AS. Option D is wrong because the configuration is valid; MED can be set on outbound updates using a route-map with the 'set metric' command, and this is a common practice for influencing path selection in neighboring ASes.

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MCQmedium

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?

A.Routes received from 10.0.0.2 will have their origin set to incomplete, making them less preferred compared to IGP origin.

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

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

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

AnswerA

Correct. Incomplete origin is the least preferred.

Why this answer

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.

Exam trap

Cisco often tests the directionality of route-maps (in vs out) and the fact that origin can be modified with a route-map, leading candidates to mistakenly think the route-map applies to outbound updates or that origin is immutable.

How to eliminate wrong answers

Option B is wrong because the route-map is applied 'in' (inbound), not 'out' (outbound), so it affects received routes, not sent routes. Option C is wrong because the configuration does not filter or suppress routes; it only modifies the origin attribute of received routes, and routes with origin incomplete can still be advertised to other peers. Option D is wrong because the origin attribute can be changed using a route-map with the 'set origin' command; this is a valid BGP configuration.

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Drag & Dropmedium

Drag and drop the steps of BGP route aggregation and suppress-map process into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Aggregation requires creating a prefix-list to match specific subnets, then a route-map to suppress more-specifics, applying it under the aggregate-address command, and finally verifying the summary route.

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MCQmedium

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?

A.All routes from neighbor 10.0.0.2 are accepted except those matching 10.0.0.0/8.

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

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

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

AnswerA

Correct. The deny statement blocks the specific prefix, and the permit allows everything else.

Why this answer

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.

Exam trap

Cisco often tests the interaction between route-map sequence numbers and the implicit deny at the end of a route-map, leading candidates to forget that a permit statement with no match (like sequence 20) is needed to allow all other routes through.

How to eliminate wrong answers

Option B is wrong because the configuration denies routes matching 10.0.0.0/8, not accepts them. Option C is wrong because route-maps can start with a deny statement; there is no requirement for the first statement to be permit. Option D is wrong because the prefix-list uses 'permit' to define which prefixes are matched by the route-map's deny clause; using 'deny' in the prefix-list would not match the intended prefixes.

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Matchingmedium

Drag and drop each BGP attribute on the left to the value that is preferred (highest or lowest) during path selection on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Highest

Lowest

Why these pairings

Higher weight is preferred; higher LOCAL_PREF is preferred; shorter AS_PATH length is preferred; lower MULTI_EXIT_DISC is preferred; lower IGP metric to next-hop is preferred.

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Drag & Dropmedium

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

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

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.

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MCQmedium

An enterprise network uses BGP to connect to two ISPs. The router has a BGP configuration that includes the command 'bgp bestpath med missing-as-worst'. The engineer notices that routes from ISP-A that do not have the MED attribute are being preferred over routes from ISP-B that have a MED of 50. What is the effect of the 'bgp bestpath med missing-as-worst' command?

A.It causes routes without the MED attribute to be treated as having the highest MED value, making them less preferred.

B.It causes routes without the MED attribute to be treated as having a MED value of 0, making them more preferred.

C.It causes routes with the MED attribute to be ignored during path selection.

D.It causes the router to add a MED value of 0 to all routes that are missing MED.

AnswerA

Correct because the command sets missing MED to the worst possible value, which is the highest MED, making those routes less preferred in path selection.

Why this answer

The 'bgp bestpath med missing-as-worst' command instructs the router to treat routes that lack the MED (Multi-Exit Discriminator) attribute as if they have the highest possible MED value (effectively infinity). Since a higher MED value is less preferred in BGP path selection, routes without MED become the least preferred among paths from the same AS. In this scenario, routes from ISP-A missing MED are treated as having a very high MED, making them less preferred than routes from ISP-B with a MED of 50, which contradicts the observed behavior, but the command's intended effect is to make missing-MED routes less preferred.

Exam trap

Cisco often tests the default behavior versus the modified behavior with 'missing-as-worst', and the trap here is that candidates mistakenly think the command makes missing-MED routes more preferred (like a MED of 0) instead of less preferred (like the highest MED).

How to eliminate wrong answers

Option B is wrong because the command does not treat missing MED as 0; treating missing MED as 0 would make those routes more preferred, which is the default behavior without this command. Option C is wrong because the command does not ignore MED during path selection; it specifically modifies how missing MED is evaluated, but MED is still considered. Option D is wrong because the command does not add a MED value of 0 to routes; it only changes the comparison logic so that missing MED is treated as the highest value, not a literal addition of 0.

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Matchingmedium

Drag and drop each BGP attribute on the left to its matching type on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Well-known mandatory

Well-known discretionary

Optional non-transitive

Optional transitive

Why these pairings

AS_PATH and NEXT_HOP are well-known mandatory; LOCAL_PREF is well-known discretionary; MED is optional non-transitive; COMMUNITY is optional transitive.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show bgp ipv4 unicast neighbors 10.0.1.2 received-routes Network Next Hop Metric LocPrf Weight Path *> 192.168.1.0/24 10.0.1.2 0 100 0 65050 i *> 192.168.2.0/24 10.0.1.2 0 100 0 65050 i *> 10.10.10.0/24 10.0.1.2 0 100 0 65050 65100 i Total number of prefixes 3 Based on this output, what can be concluded?

A.All three routes are installed in the routing table of R1.

B.R1 has received 3 prefixes from neighbor 10.0.1.2.

C.R1 is advertising these three routes to neighbor 10.0.1.2.

D.The route 10.10.10.0/24 has a weight of 0, meaning it is not preferred.

AnswerB

The command shows all routes received from the neighbor, and the total is 3 prefixes.

Why this answer

The command `show bgp ipv4 unicast neighbors 10.0.1.2 received-routes` displays all BGP routes that have been received from the specified neighbor, regardless of whether they are installed in the routing table. The output shows three prefixes, confirming that R1 has received exactly three routes from neighbor 10.0.1.2. The asterisk (*) and greater-than (>) symbols indicate the route is valid and best, but this does not guarantee installation in the routing table if a better administrative distance route exists.

Exam trap

Cisco often tests the distinction between `received-routes`, `routes`, and `advertised-routes` in BGP show commands, and the trap here is that candidates assume the asterisk and greater-than symbols guarantee the route is in the routing table, when they only indicate BGP best-path selection within the BGP table.

How to eliminate wrong answers

Option A is wrong because the received-routes output shows prefixes that are valid and best within BGP, but they may not be installed in the routing table if a route with a lower administrative distance (e.g., an OSPF or static route) is present; the command does not confirm routing table installation. Option C is wrong because the command specifically shows routes received from the neighbor, not routes advertised to the neighbor; to see advertised routes, one would use `show bgp ipv4 unicast neighbors 10.0.1.2 advertised-routes`. Option D is wrong because a weight of 0 is the default value for routes learned from eBGP neighbors and does not indicate that the route is not preferred; BGP best-path selection uses weight as the first criterion, but a weight of 0 simply means no local preference was manually assigned, and the route can still be the best path if no higher-weight route exists.

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MCQeasy

A network engineer is configuring BGP on a router that will be used for BGP route summarization. The router receives multiple more-specific prefixes from its eBGP peers. The engineer wants to advertise a summary route to the iBGP peers without advertising the more-specific routes. Which command should the engineer use to suppress the more-specific routes while still installing them in the local routing table?

A.Use the 'aggregate-address' command with the 'summary-only' keyword.

B.Use the 'network' command to advertise the summary route.

C.Use the 'summary-address' command under the BGP address family.

D.Use the 'redistribute' command to inject the summary route into BGP.

AnswerA

Correct because this command creates an aggregate route and suppresses the advertisement of more-specific routes to BGP peers.

Why this answer

The 'aggregate-address' command with the 'summary-only' keyword in BGP creates a summary route from more-specific prefixes and suppresses the advertisement of those more-specific routes to BGP peers, while still keeping them in the local routing table. This meets the requirement of advertising only the summary to iBGP peers without removing the more-specific routes from the router's own RIB.

Exam trap

Cisco often tests the distinction between suppressing routes from advertisement versus removing them from the local table, and candidates mistakenly think 'summary-only' removes the more-specific routes from the router, but it only suppresses their advertisement to BGP peers.

How to eliminate wrong answers

Option B is wrong because the 'network' command advertises a prefix only if it exists exactly in the routing table; it does not suppress more-specific routes or create an aggregate from them. Option C is wrong because 'summary-address' is not a valid BGP command; the correct command for BGP summarization is 'aggregate-address'. Option D is wrong because 'redistribute' injects routes from another protocol into BGP but does not create a summary or suppress more-specific prefixes; it would advertise all redistributed routes, including the more-specific ones.

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MCQeasy

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?

A.The route was learned from an internal BGP peer.

B.The route is from AS 65050 and is the best path.

C.The route has a local preference of 0.

D.The route is not valid because it is external.

AnswerB

The AS_PATH shows 65050, and the path is marked as 'best'.

Why this answer

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.

Exam trap

Cisco often tests the distinction between 'valid' and 'best' — candidates may incorrectly assume that an external route is automatically invalid or that 'external' implies a problem, but the output clearly shows the route is both valid and best.

How to eliminate wrong answers

Option A is wrong because the route is learned from an external BGP peer (indicated by 'external' in the status flags and the neighbor IP 10.0.1.2, which is not in the same AS as the router's BGP configuration). Option C is wrong because the output explicitly shows 'localpref 100', not 0; local preference defaults to 100 for routes from external peers unless modified. Option D is wrong because the route is explicitly marked as 'valid' in the output, and being external does not make it invalid; external routes are valid if they pass BGP path validation.

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MCQhard

A network engineer is configuring BGP on a Cisco router that is part of an enterprise network with multiple BGP peers. The router receives routes from two different ISPs. The engineer wants to ensure that only specific prefixes from ISP-A are installed in the routing table, while all other routes from ISP-A are ignored. Additionally, the engineer wants to accept all routes from ISP-B. Which BGP feature should be used on the router for the peering with ISP-A?

A.Apply a distribute list under the BGP neighbor configuration for ISP-A.

B.Configure a network statement under BGP for the desired prefixes.

C.Use the default-information originate command under BGP.

D.Apply a route map to the neighbor using the route-map command in the inbound direction.

AnswerA

Correct because a distribute list with a prefix list can filter incoming routes based on prefix, allowing only specific prefixes.

Why this answer

A distribute list applied under the BGP neighbor configuration for ISP-A allows the engineer to filter specific prefixes using an access list or prefix list, ensuring only the desired prefixes are installed in the routing table while all others from ISP-A are ignored. This is the correct tool for inbound route filtering on a per-neighbor basis, as it directly controls which routes are accepted into the BGP table and subsequently the routing table.

Exam trap

Cisco often tests the distinction between filtering incoming routes (distribute list or route map) versus originating routes (network statement) or generating defaults (default-information originate), leading candidates to confuse route map with distribute list when both can filter, but the question explicitly asks for the feature that 'should be used' and distribute list is the precise answer for prefix-only filtering without attribute manipulation.

How to eliminate wrong answers

Option B is wrong because a network statement under BGP is used to originate a prefix into BGP, not to filter incoming routes from a neighbor. Option C is wrong because the default-information originate command is used to generate a default route into BGP, not to filter specific prefixes from a peer. Option D is wrong because while a route map can be used for inbound filtering, the question specifies a distribute list as the correct feature; a route map is more complex and typically used for attribute manipulation, but a distribute list is the simpler, direct filtering mechanism for prefix-based control.

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Multi-Selecteasy

Which two statements about BGP neighbor states are true? (Choose two.)

Select 2 answers

A.In the Idle state, BGP is waiting for a start event before initiating a TCP connection.

B.In the Active state, BGP is actively trying to establish a TCP connection with the neighbor.

C.In the Established state, BGP has sent an OPEN message but has not yet received an OPEN message from the peer.

D.In the OpenSent state, BGP is waiting for the TCP connection to complete.

E.In the Connect state, BGP is actively trying to establish a TCP connection.

AnswersA, B

Correct: Idle is the initial state; BGP does not initiate a TCP connection until a start event (e.g., neighbor configuration) occurs.

Why this answer

The BGP neighbor state machine includes Idle, Connect, Active, OpenSent, OpenConfirm, and Established. In the Idle state, BGP does not initiate any connection and may be waiting for a start event. In the Active state, BGP is actively trying to establish a TCP connection.

In the Established state, BGP has successfully formed a peering session and is exchanging routing updates. The OpenSent state is when BGP has sent an OPEN message and is waiting for an OPEN message from the peer. The Connect state is when BGP is waiting for the TCP connection to complete.

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MCQmedium

A network engineer is configuring BGP on a Cisco router that connects to two ISPs. The router has a default route pointing to each ISP. The engineer wants to load balance outbound traffic across both ISPs. The router receives a default route from both ISPs. Which BGP configuration approach will allow the router to install both default routes in the routing table and load balance traffic?

A.Configure the maximum-paths command under the BGP address family and use the bgp bestpath as-path multipath-relax command.

B.Configure the network command to advertise the default route from both ISPs.

C.Set the local preference to the same value on both default routes.

D.Use the redistribute command to redistribute the default routes into BGP.

AnswerA

Correct because maximum-paths allows multiple paths to be installed, and multipath-relax ignores AS_PATH length differences, enabling load balancing across different ASes.

Why this answer

Option A is correct because the `maximum-paths` command under the BGP address family enables the router to install multiple paths for the same prefix (in this case, the default route 0.0.0.0/0) into the routing table. The `bgp bestpath as-path multipath-relax` command is necessary because the two default routes from different ISPs will have different AS_PATH lengths; this command relaxes the requirement for equal AS_PATH length, allowing the router to consider them as multipath candidates. Together, they allow both default routes to be installed and used for load balancing outbound traffic.

Exam trap

Cisco often tests the nuance that simply having equal BGP path attributes (like local preference) does not enable multipath installation; candidates must remember that `maximum-paths` and `multipath-relax` are explicitly required to install and load balance multiple BGP routes, even for default routes.

How to eliminate wrong answers

Option B is wrong because the `network` command is used to inject a prefix into BGP from the IP routing table, not to install received routes; the router already receives the default routes from the ISPs, so advertising them again is irrelevant to load balancing. Option C is wrong because setting the same local preference on both default routes only ensures they have equal preference in the BGP best-path selection process, but without `maximum-paths` and `multipath-relax`, the router will still select only one best path and install a single default route. Option D is wrong because `redistribute` is used to import routes from another routing protocol into BGP, not to control how received BGP routes are installed; redistributing the default routes would create a new BGP route, but it does not enable multipath installation of the received routes.

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MCQmedium

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?

A.This is an iBGP session because the remote AS matches the local AS.

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

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

D.The configuration is invalid because iBGP requires a loopback interface.

AnswerA

Correct. When remote-as equals the local AS, it is iBGP.

Why this answer

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.

Exam trap

Cisco often tests the distinction between iBGP and eBGP based solely on AS numbers, leading candidates to mistakenly think subnet differences or interface types determine the session type.

How to eliminate wrong answers

Option B is wrong because eBGP is defined by different AS numbers, not by subnet differences; iBGP can operate between neighbors in different subnets. Option C is wrong because next-hop-self is not automatically set for iBGP neighbors; it must be explicitly configured with the 'neighbor x.x.x.x next-hop-self' command. Option D is wrong because iBGP does not require a loopback interface; while loopbacks are commonly used for stability, the configuration is valid with any interface IP.

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MCQmedium

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

A.Highest weight

B.Highest local preference

C.Shortest AS-path

D.Lowest MED

AnswerA

Correct. Weight is the first attribute compared in BGP best path selection.

Why this answer

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.

Exam trap

Cisco often tests the exact order of BGP path selection attributes, and the trap here is that candidates mistakenly think local preference or AS-path length is the first comparison, because those are more commonly discussed in multi-AS designs, but weight always comes first in Cisco's implementation.

How to eliminate wrong answers

Option B is wrong because highest local preference is compared after weight, not first. Option C is wrong because shortest AS-path is the third attribute compared, after weight and local preference. Option D is wrong because lowest MED is compared after AS-path length (and other attributes like origin type) in the BGP decision process.

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MCQmedium

An enterprise network has two routers, R1 and R2, both running BGP. R1 is an eBGP speaker with ISP1, and R2 is an eBGP speaker with ISP2. Both routers are in the same AS 65000. The engineer wants to ensure that traffic from the enterprise to the Internet prefers the path through ISP1 when both links are up. R1 learns a default route from ISP1, and R2 learns a default route from ISP2. Which BGP attribute should the engineer modify on R1 to influence outbound traffic selection?

A.Set a higher local preference on R1 for the default route learned from ISP1.

B.Set a lower MED on R1 for the default route learned from ISP1.

C.Prepend AS 65000 multiple times on R2's updates to ISP2.

D.Configure a community on R1 to mark the default route as no-export.

AnswerA

Correct because local preference influences outbound path selection within the AS; a higher value makes the route more preferred.

Why this answer

Local preference is the BGP attribute used to influence outbound traffic from an AS. It is propagated within the AS and a higher value is preferred. By setting a higher local preference on R1 for the default route learned from ISP1, R1 will prefer that route over the default route from ISP2, ensuring traffic from the enterprise to the Internet exits via ISP1.

Exam trap

Cisco often tests the distinction between attributes that influence outbound traffic (local preference, weight) versus inbound traffic (MED, AS path prepending), and the trap here is confusing MED or AS path prepending as tools for outbound path selection.

How to eliminate wrong answers

Option B is wrong because MED (Multi-Exit Discriminator) is used to influence inbound traffic into an AS, not outbound traffic; lowering MED on R1 would affect how ISP1 selects paths to reach prefixes inside AS 65000, not how R1 chooses a default route. Option C is wrong because AS path prepending is applied to outbound updates to influence inbound traffic from ISPs, making a path less preferred by lengthening the AS_PATH; it does not affect R1's outbound traffic selection. Option D is wrong because the no-export community prevents a route from being advertised to eBGP peers, which would block the default route from being sent to ISP1 or ISP2, but does not influence R1's preference for outbound traffic.

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Multi-Selectmedium

Which two statements about BGP path attributes are true? (Choose two.)

Select 2 answers

A.The AS_PATH attribute is well-known mandatory.

B.The LOCAL_PREF attribute is well-known discretionary.

C.The MED attribute is well-known mandatory.

D.The ORIGIN attribute is optional transitive.

E.The COMMUNITY attribute is well-known mandatory.

AnswersA, B

Correct because AS_PATH is always included in BGP updates and is well-known mandatory.

Why this answer

The ORIGIN attribute is well-known mandatory. The COMMUNITY attribute is optional transitive.

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Matchingmedium

Drag and drop each BGP community on the left to its standard behavior on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Do not advertise to any eBGP peer outside the AS

Do not advertise to any peer (eBGP or iBGP)

Do not advertise outside the local confederation

Do not advertise to any eBGP peer

Graceful shutdown of the route

Why these pairings

NO_EXPORT prevents advertisement outside the AS; NO_ADVERTISE prevents advertisement to any peer; LOCAL_AS prevents advertisement outside the local confederation; NO_PEER prevents advertisement to any eBGP peer; GSHUT signals graceful shutdown.

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MCQhard

An engineer is configuring BGP on a router that will act as a route reflector to reduce iBGP peering requirements. The router has several iBGP peers. The engineer wants to ensure that the route reflector does not modify the next-hop attribute of routes it reflects to its clients. Which configuration command should the engineer use?

A.Configure 'neighbor next-hop-unchanged' under the BGP address family for the route reflector clients.

B.Configure 'no bgp next-hop-self' under the BGP address family for the route reflector clients.

C.Configure 'bgp route-reflector' under the BGP address family.

D.Configure 'neighbor next-hop-self' on the route reflector for its clients.

AnswerA

Correct because this command explicitly instructs the router to not modify the next-hop attribute when sending routes to the specified neighbor, preserving the original next-hop.

Why this answer

Option A is correct because the 'neighbor next-hop-unchanged' command under the BGP address family instructs the route reflector to preserve the original next-hop attribute when reflecting routes to its clients. By default, a route reflector may modify the next-hop to its own address, but this command overrides that behavior, ensuring the next-hop remains as received from the non-client iBGP peer. This is essential in designs where clients must see the original next-hop for optimal path selection or to avoid unnecessary routing hops.

Exam trap

Cisco often tests the distinction between 'neighbor next-hop-unchanged' and 'neighbor next-hop-self', where candidates mistakenly think that disabling 'next-hop-self' (option B) is sufficient to preserve the next-hop, but the correct command is the explicit 'next-hop-unchanged' to override any default or configured modifications.

How to eliminate wrong answers

Option B is wrong because 'no bgp next-hop-self' removes the default next-hop-self behavior for eBGP-learned routes, but it does not specifically control the next-hop attribute for routes reflected by a route reflector; it is a global or address-family command that affects all iBGP peers, not just clients. Option C is wrong because 'bgp route-reflector' is not a valid Cisco IOS command; the correct command to enable route reflection is 'neighbor route-reflector-client' under the BGP address family. Option D is wrong because 'neighbor next-hop-self' on the route reflector for its clients would force the next-hop to be changed to the route reflector's own IP address, which is the opposite of what the engineer wants (to leave the next-hop unchanged).

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Drag & Dropmedium

Drag and drop the steps of iBGP route reflection configuration steps into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Route reflection requires first enabling BGP, then configuring the cluster ID, designating the route reflector client, and finally verifying the reflection behavior.

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MCQeasy

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

A.Local preference

B.MED

C.Weight

D.AS-path

AnswerA

Correct. Local preference is used within an AS and is propagated to iBGP peers.

Why this answer

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.

Exam trap

Cisco often tests the distinction between attributes that are propagated within an AS (local preference) versus those that are not (weight), or those that influence inbound versus outbound traffic (MED vs. local preference).

How to eliminate wrong answers

Option B (MED) is wrong because MED (Multi-Exit Discriminator) is a metric used to influence inbound traffic from neighboring ASes and is not propagated to iBGP peers; it is exchanged only between eBGP peers. Option C (Weight) is wrong because weight is a Cisco-proprietary attribute that is local to the router and is not propagated to any BGP peers, iBGP or eBGP. Option D (AS-path) is wrong because AS-path is a well-known mandatory attribute used for loop prevention and path selection, but it is not used to indicate preference within an AS; it is propagated to all BGP peers but does not serve the described function.

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Drag & Dropmedium

Drag and drop the steps of BGP confederations setup between sub-ASes into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Confederation setup requires enabling BGP, configuring the confederation identifier and sub-AS list, then peering between sub-ASes, and finally verifying the confederation membership.

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MCQmedium

A network engineer is troubleshooting BGP peering between two routers in different autonomous systems. The peering is established over a directly connected Ethernet link. The engineer notices that the BGP session is flapping every few minutes. The configuration on both routers appears correct, and the IP connectivity is stable. The engineer checks the BGP logs and sees messages like 'BGP-3-NOTIFICATION: sent 4/0 (Hold Timer Expired)'. What is the most likely cause of this issue?

A.The hold timer values are mismatched between the two routers.

B.The MTU on the link is mismatched, causing BGP packets to be fragmented.

C.The TTL for eBGP is set to 1, and the routers are not directly connected.

D.The BGP update timer is set too high, causing delays in sending updates.

AnswerA

Correct because a hold timer mismatch causes the router with the smaller hold time to expire, leading to session flaps.

Why this answer

The BGP notification 'Hold Timer Expired' indicates that the router did not receive keepalive or update messages within the configured hold time. When hold timers are mismatched between two eBGP peers, the router with the shorter hold timer will expire first, causing the session to reset. Since the IP connectivity is stable and the configuration appears correct, a mismatch in hold timer values is the most direct cause of the flapping session.

Exam trap

Cisco often tests the distinction between hold timer mismatch (which causes a notification and session reset) versus other common BGP issues like MTU or TTL, where candidates may incorrectly assume that any BGP flapping is due to connectivity or packet loss rather than timer negotiation.

How to eliminate wrong answers

Option B is wrong because MTU mismatch would cause packet fragmentation or loss, not a hold timer expiration; BGP uses TCP which handles fragmentation, and the issue would manifest as TCP retransmissions or connection resets, not a hold timer expiry. Option C is wrong because the peering is over a directly connected Ethernet link, so the default TTL of 1 for eBGP is appropriate and would not cause flapping; if the routers were not directly connected, the session would never establish. Option D is wrong because the BGP update timer (or advertisement interval) controls the rate of sending updates, not the receipt of keepalives; a high update timer would not cause a hold timer expiration because keepalives are sent independently every one-third of the hold time.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show bgp ipv4 unicast 192.168.1.0 BGP routing table entry for 192.168.1.0/24, version 10 Paths: (2 available, best #2, table default) Advertised to update-groups: 1 Refresh Epoch 1 Local 10.0.0.2 from 10.0.1.2 (10.0.0.2) Origin IGP, metric 0, localpref 100, valid, internal rx pathid: 0, tx pathid: 0x0 Local, (received & used) 10.0.0.3 from 10.0.1.3 (10.0.0.3) Origin IGP, metric 0, localpref 200, valid, internal, best rx pathid: 0, tx pathid: 0x0 Based on this output, what can be concluded?

A.The path from 10.0.1.2 is the best path because it is received first.

B.The path from 10.0.1.3 is preferred because of a higher local preference.

C.Both paths are from external BGP peers.

D.The path from 10.0.1.2 is marked as best because it has a lower metric.

AnswerB

Local preference is 200 for path #2 (from 10.0.1.3) versus 100 for path #1. Higher local preference is preferred in BGP best path selection.

Why this answer

The output shows two BGP paths for 192.168.1.0/24, both with Origin IGP and metric 0. The path from 10.0.1.3 has a local preference of 200, while the path from 10.0.1.2 has a local preference of 100. BGP selects the path with the highest local preference as the best path, making the path from 10.0.1.3 the best (marked as 'best' in the output).

Exam trap

Cisco often tests the BGP best path selection order, and the trap here is that candidates may confuse local preference with MED or assume that the first received route is preferred, when in fact local preference is evaluated much earlier in the decision process.

How to eliminate wrong answers

Option A is wrong because BGP does not select the best path based on which route is received first; it uses a deterministic decision process where local preference is evaluated before arrival order. Option C is wrong because both paths are marked as 'internal' (iBGP), not external (eBGP), as indicated by the 'internal' keyword in the path attributes. Option D is wrong because both paths have the same metric (0), and BGP does not use metric (MED) as a tiebreaker before local preference; the higher local preference of 200 on the path from 10.0.1.3 is the decisive factor.

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MCQhard

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?

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

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

C.The BGP session is up and functioning normally.

D.The neighbor has sent 5 updates and received 3 updates.

AnswerC

The state is Established, messages are being exchanged, and timers are within expected ranges.

Why this answer

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.

Exam trap

Cisco often tests the misinterpretation of message statistics, where candidates incorrectly assume 'Sent' and 'Rcvd' are from the neighbor's perspective rather than the local router's, leading to option D being chosen.

How to eliminate wrong answers

Option A is wrong because the BGP state is 'Established', not 'Idle', and a last read of 15 seconds ago is within the 90-second hold time, indicating normal operation. Option B is wrong because the remote AS is 65050, which is different from the local AS (not shown but implied by 'external link'), making this an eBGP peer, not an iBGP peer. Option D is wrong because the output shows the router sent 5 updates and received 3 updates, not the neighbor; the neighbor's sent/received counts are the reverse of what is shown.

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MCQhard

A network engineer runs the following command on Router R1: R1# show bgp ipv4 unicast 10.10.10.0 BGP routing table entry for 10.10.10.0/24, version 20 Paths: (2 available, best #1, 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, best rx pathid: 0, tx pathid: 0x0 65050 65100 65200 10.0.1.3 from 10.0.1.3 (10.0.0.3) Origin IGP, metric 0, localpref 100, weight 0, valid, external rx pathid: 0, tx pathid: 0x0 Based on this output, what can be concluded?

A.Path #2 is the best path because it has a longer AS_PATH, indicating more specific routing.

B.Path #1 is the best path because it has a shorter AS_PATH length.

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

D.Path #1 is the best path because it is received from a higher IP address.

AnswerB

Path #1 has AS_PATH length 2 (65050 65100) while path #2 has length 3 (65050 65100 65200). Shorter AS_PATH is preferred.

Why this answer

B is correct because BGP selects the best path based on the shortest AS_PATH length when all other attributes (weight, local preference, origin) are equal. In the output, Path #1 has an AS_PATH of '65050 65100' (2 AS numbers) while Path #2 has '65050 65100 65200' (3 AS numbers), making Path #1 the best path. The 'best #1' annotation confirms this selection.

Exam trap

Cisco often tests the AS_PATH length comparison by presenting two paths with different AS_PATH lengths but identical other attributes, expecting candidates to know that shorter AS_PATH is preferred, not longer.

How to eliminate wrong answers

Option A is wrong because a longer AS_PATH does not indicate more specific routing; BGP prefers shorter AS_PATH lengths, not longer ones. Option C is wrong because the paths are not equally preferred; Path #1 is explicitly marked as best due to shorter AS_PATH, so tie-breaking rules like router ID are not invoked. Option D is wrong because BGP does not use the IP address of the next-hop or neighbor as a tie-breaker for best path selection; the decision is based on AS_PATH length in this case.

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MCQeasy

A network engineer runs the following command on Router R1: R1# show bgp ipv4 unicast neighbors 10.0.1.2 advertised-routes Network Next Hop Metric LocPrf Weight Path *> 172.16.0.0/16 10.0.1.1 0 100 0 i *> 172.16.1.0/24 10.0.1.1 0 100 0 i Total number of prefixes 2 Based on this output, what can be concluded?

A.R1 is receiving 2 prefixes from neighbor 10.0.1.2.

B.R1 is advertising 2 prefixes to neighbor 10.0.1.2.

C.Neighbor 10.0.1.2 is advertising these routes to R1.

D.The routes are being advertised with a next hop of 10.0.1.2.

AnswerB

The command explicitly shows routes that R1 advertises to the neighbor. The total is 2 prefixes.

Why this answer

The command 'show bgp ipv4 unicast neighbors 10.0.1.2 advertised-routes' specifically displays the routes that Router R1 is sending to the BGP neighbor at 10.0.1.2. The output shows two prefixes (172.16.0.0/16 and 172.16.1.0/24) with a next hop of 10.0.1.1 (R1's own interface), confirming these are routes R1 is advertising. Therefore, option B is correct.

Exam trap

Cisco often tests the distinction between 'advertised-routes' and 'received-routes' keywords, trapping candidates who confuse which device is the sender versus receiver in the BGP neighbor relationship.

How to eliminate wrong answers

Option A is wrong because the command shows advertised routes, not received routes; to see received routes, one would use 'show bgp ipv4 unicast neighbors 10.0.1.2 received-routes'. Option C is wrong because the output indicates R1 is the advertiser, not the neighbor; the neighbor 10.0.1.2 is the recipient of these routes. Option D is wrong because the next hop in the output is 10.0.1.1 (R1's own address), not 10.0.1.2, which would be the case if R1 were receiving routes from the neighbor.

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Matchinghard

Drag and drop each BGP community on the left to its standard behavior on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Do not advertise to eBGP peers (except within confederation)

Do not advertise to any peer

Do not advertise to external peers (confederation boundary)

Do not advertise to any BGP peer

Advertise to all BGP peers (default behavior)

Why these pairings

NO_EXPORT prevents advertisement outside confederation; NO_ADVERTISE prevents any advertisement; LOCAL_AS prevents advertisement to external peers; NO_PEER prevents advertisement to any peer; INTERNET advertises to all BGP peers.

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MCQeasy

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

A.0

B.100

C.32768

D.1

AnswerA

Correct. Weight defaults to 0 for routes learned from BGP neighbors.

Why this answer

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.

Exam trap

Cisco often tests the distinction between the default weight for locally originated routes (32768) versus routes learned from a neighbor (0), causing candidates to mistakenly choose 32768 when asked about learned routes.

How to eliminate wrong answers

Option B (100) is wrong because 100 is the default administrative distance for IBGP routes, not the default BGP weight. Option C (32768) is wrong because 32768 is the default weight for locally originated routes (e.g., routes injected via the network command), not for routes learned from a neighbor. Option D (1) is wrong because there is no BGP attribute or default value of 1 for weight; weight values range from 0 to 65535, and 0 is the default for learned routes.

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Drag & Dropmedium

Drag and drop the steps of BGP policy application (route-map, prefix-list, AS-path ACL) into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Policy application starts with defining match criteria (prefix-list or AS-path ACL), then creating a route-map with permit/deny and set actions, applying it to a neighbor, and finally verifying the policy effect.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show bgp summary BGP router identifier 10.0.0.1, local AS number 65001 BGP table version is 14, main routing table version 14 4 network entries using 1152 bytes of memory 4 path entries using 320 bytes of memory 2/1 BGP path/bestpath attribute entries using 560 bytes of memory 0 BGP route reflector client to client reflections 2 BGP community entries using 80 bytes of memory Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 10.0.1.2 4 65002 2345 2346 14 0 0 00:12:34 3 10.0.1.3 4 65003 1234 1235 14 0 0 00:08:21 2 10.0.1.4 4 65004 567 568 14 0 0 00:05:45 0 Based on this output, what can be concluded?

A.Neighbor 10.0.1.4 is in the 'Active' state because it received 0 prefixes.

B.Neighbor 10.0.1.4 has sent 0 prefixes to R1.

C.Neighbor 10.0.1.4 is not advertising any prefixes to R1.

D.The BGP session with 10.0.1.4 is down.

AnswerC

The 0 in the PfxRcd column means R1 has received no prefixes from 10.0.1.4. This is likely because 10.0.1.4 has no routes to advertise or is filtering outbound.

Why this answer

The 'State/PfxRcd' column shows the number of prefixes received from each neighbor. Neighbor 10.0.1.4 has a value of 0, meaning it has not advertised any prefixes to R1. The session is established (Up/Down shows 00:05:45), so the neighbor is reachable and the BGP session is up, but it is not sending any prefixes.

Exam trap

The trap here is that candidates may misinterpret the '0' in the 'State/PfxRcd' column as a session failure or that R1 is not sending prefixes, when it actually indicates the neighbor is not advertising any prefixes to R1.

How to eliminate wrong answers

Option A is wrong because the neighbor is in the 'Established' state (indicated by the Up/Down timer), not 'Active'; the 'Active' state would show a different status in the State/PfxRcd column. Option B is wrong because the 'MsgSent' column (568) indicates messages sent to the neighbor, but the 'State/PfxRcd' column shows prefixes received from the neighbor, not sent by R1. Option D is wrong because the Up/Down timer of 00:05:45 confirms the BGP session is up and established, not down.

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MCQmedium

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?

A.It allows the eBGP session to be established with a neighbor that is not directly connected, with a maximum of 2 hops.

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

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

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

AnswerA

Correct. ebgp-multihop increases the TTL to allow multi-hop eBGP.

Why this answer

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.

Exam trap

Cisco often tests the distinction between ebgp-multihop (which adjusts TTL for non-directly connected peering) and BGP multipath (which enables load balancing), causing candidates to confuse the two features.

How to eliminate wrong answers

Option B is wrong because the command to set the maximum number of prefixes received from a neighbor is 'neighbor maximum-prefix', not ebgp-multihop. Option C is wrong because BGP multipath for load balancing is configured with 'maximum-paths' (or 'maximum-paths ibgp'/'maximum-paths ebgp'), not with ebgp-multihop. Option D is wrong because ebgp-multihop does not enable BGP multipath; it only adjusts the TTL to allow non-directly connected eBGP peering, while multipath is a separate feature for load balancing across multiple equal-cost paths.

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Drag & Dropmedium

Drag and drop the steps of BGP graceful restart negotiation steps into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

First, both peers advertise the graceful restart capability in the OPEN message. Then they exchange the restart time and stale-path timer via capabilities. Next, the helper router marks routes as stale upon session failure.

After that, the restarting router re-establishes the session. Finally, the helper removes stale routes if not refreshed.

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Drag & Dropmedium

Drag and drop the steps of iBGP route reflection configuration into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

First, you enable the BGP process and define the local AS. Then you configure the router as a route reflector using the neighbor route-reflector-client command. Next, you specify the cluster ID if needed, then adjust the next-hop behavior with next-hop-self.

Finally, you verify the configuration with show ip bgp neighbors.

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MCQhard

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?

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

B.Path #2 is the best path because it has a shorter AS_PATH.

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

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

AnswerB

Path #2 has AS_PATH length 1 (65050) while path #1 has length 2 (65050 65100). Shorter AS_PATH is preferred.

Why this answer

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.

Exam trap

Cisco often tests the BGP best-path selection order, and the trap here is that candidates may assume that a longer AS_PATH indicates a more specific or preferred route, or that the path with the higher neighbor IP address is chosen, when in fact BGP strictly prefers the shortest AS_PATH at this stage of the decision process.

How to eliminate wrong answers

Option A is wrong because a longer AS_PATH is actually less preferred in BGP best-path selection, not more specific; AS_PATH length is a metric for path preference, not route specificity. Option C is wrong because the paths are not equally preferred; the output explicitly shows that Path #2 is the best due to a shorter AS_PATH, and BGP tie-breaking rules are applied sequentially, not arbitrarily. Option D is wrong because BGP does not compare neighbor IP addresses as a tie-breaker at this stage; the shorter AS_PATH is the decisive factor here, and router ID or IP address comparisons only come into play much later in the BGP decision process.

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