300-410 Route Maps and Route Filtering Practice Test 2 — 15 Questions

Question 1

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 192.168.1.2
BGP neighbor is 192.168.1.2,  remote AS 65001, external link
  BGP version 4, remote router ID 10.2.2.2
  BGP state = Established, up for 00:15:00
  Last read 00:00:05, hold time is 180, keepalive interval is 60 seconds
  Neighbor sessions:
    1 active, is 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
  Message statistics:
    InQ depth is 0
    OutQ depth is 0
                         Sent       Rcvd
    Opens:                  1          1
    Notifications:          0          0
    Updates:               10          5
    Keepalives:            15         15
    Route Refresh:          0          0
    Total:                 26         21
  Default minimum time between advertisement runs is 30 seconds

For address family: IPv4 Unicast
  Session: 192.168.1.2
  BGP table version 14, neighbor version 14/0
  Output queue size : 0
  Index 1, Advertise bit 0
  1 update-group member
  Incoming update prefix filter list: FILTER_IN
  Outgoing update prefix filter list: FILTER_OUT
                                   Sent       Rcvd
  Prefixes:                           2          2
  Updates:                           10          5

Based on this output, what is the effect of the prefix lists?

Accepted Answer

The prefix lists FILTER_IN and FILTER_OUT are allowing only 2 prefixes in each direction.. The output shows that incoming and outgoing prefix filters (FILTER_IN and FILTER_OUT) are applied. The prefixes sent and received are both 2, indicating that the filters are allowing exactly 2 prefixes in each direction. The correct answer is that the prefix lists are filtering routes to only 2 prefixes.

Answer

The prefix lists are blocking all prefixes.

Answer

The prefix lists are not applied because the session is established.

Answer

The prefix lists are misconfigured and causing route flapping.

Question 2

A network engineer runs the following command on Router R1:

R1# show ip route vrf CUSTOMER_A

Routing Table: CUSTOMER_A
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
B       10.10.10.0/24 [200/0] via 192.168.1.2, 00:10:00
B       10.20.20.0/24 [200/0] via 192.168.1.2, 00:10:00

R1# show ip bgp vpnv4 vrf CUSTOMER_A
BGP table version is 6, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete

Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 100:1 (default for vrf CUSTOMER_A)
*> 10.10.10.0/24    192.168.1.2              0             0 65001 i
*> 10.20.20.0/24    192.168.1.2              0             0 65001 i
*> 10.30.30.0/24    192.168.1.2              0             0 65001 i

Based on this output, what is the likely issue?

Accepted Answer

A route-map is filtering the route 10.30.30.0/24 from the VRF routing table.. The VRF routing table shows only two routes, but the BGP table shows three routes for the VRF. This indicates that a route-map is filtering one of the routes from being installed in the routing table. The correct answer is that a route-map is filtering the route 10.30.30.0/24.

Answer

The VRF is not properly configured.

Answer

The BGP session is down.

Answer

The route distinguisher is misconfigured.

Question 3

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 10.1.1.2 advertised-routes
BGP table version is 10, local router ID is 10.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete

Network          Next Hop            Metric LocPrf Weight Path
*> 10.10.10.0/24    0.0.0.0                  0         32768 i
*> 10.20.20.0/24    0.0.0.0                  0         32768 i

R1# show route-map
route-map BLOCK_RFC1918, permit, sequence 10
  Match clauses:
    ip address prefix-list RFC1918
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes
route-map BLOCK_RFC1918, deny, sequence 20
  Match clauses:
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes

R1# show ip prefix-list RFC1918
ip prefix-list RFC1918: 3 entries
   seq 5 deny 10.0.0.0/8 le 32
   seq 10 deny 172.16.0.0/12 le 32
   seq 15 deny 192.168.0.0/16 le 32
   seq 20 permit 0.0.0.0/0 le 32

Based on this output, what is the most likely issue?

Accepted Answer

The route-map BLOCK_RFC1918 is not applied to the BGP neighbor, so RFC 1918 routes are being advertised.. The route-map BLOCK_RFC1918 is applied to filter routes, but the advertised routes include 10.10.10.0/24 and 10.20.20.0/24, which are RFC 1918 addresses. The prefix-list RFC1918 should deny these, but the route-map is not being applied to the BGP neighbor, so routes are not filtered. The correct answer is that the route-map is not applied to the BGP neighbor.

Answer

The prefix-list RFC1918 is misconfigured and permits all routes.

Answer

The route-map is applied but the match clause is incorrect.

Answer

The BGP session is not established.

Question 4

Examine the following partial configuration on R1:

!--- R1 configuration
route-map RMAP permit 10
 match ip address prefix-list PL-1
 set metric 100
!
route-map RMAP permit 20
 set metric 200
!
router eigrp 100
 network 10.0.0.0
 redistribute ospf 1 metric 1000 100 255 1 1500 route-map RMAP
!

What is the effect of this configuration?

Accepted Answer

Routes matching prefix-list PL-1 are redistributed with metric 100; all other OSPF routes are redistributed with metric 200.. The route-map RMAP has two permit sequences. The first matches prefix-list PL-1 and sets metric to 100. The second is a catch-all permit with no match, setting metric to 200. All redistributed OSPF routes will match either sequence and have their metric set accordingly. If a route matches the first sequence, its metric is set to 100; otherwise, it matches the second and gets metric 200. There is no deny sequence, so no routes are filtered.

Answer

Only routes matching prefix-list PL-1 are redistributed into EIGRP with metric 100; all other OSPF routes are denied.

Answer

The route-map is missing a deny statement; without it, all routes are permitted with default metric.

Answer

The route-map is applied to redistribution, but the metric values are ignored because redistribute command also specifies metric.

Question 5

Consider the following configuration on router R2:

!--- R2 configuration
ip prefix-list FILTER seq 5 deny 10.1.0.0/16 le 24
ip prefix-list FILTER seq 10 permit 0.0.0.0/0 le 32
!
route-map BGP-IN permit 10
 match ip address prefix-list FILTER
!
router bgp 65000
 neighbor 192.168.1.1 route-map BGP-IN in
!

What is the effect of this configuration?

Accepted Answer

Routes within 10.1.0.0/16 with mask length 24 or shorter are denied; all other routes are permitted.. The prefix-list FILTER denies any prefix within 10.1.0.0/16 with a mask length less than or equal to 24 (i.e., 10.1.0.0/16 through 10.1.255.0/24). The permit statement allows all other prefixes. The route-map BGP-IN calls this prefix-list; since there is only one permit sequence, routes that match the deny statement in the prefix-list are implicitly denied by the route-map. Therefore, routes like 10.1.0.0/16, 10.1.1.0/24, etc., are filtered out.

Answer

All routes from neighbor 192.168.1.1 are accepted; the prefix-list is not applied correctly because the route-map only has a permit sequence.

Answer

Only routes with mask length exactly 24 are denied; all other routes are permitted.

Answer

The configuration is incomplete; a route-map must have a deny statement to filter routes.

Question 6

Examine the following configuration on R3:

!--- R3 configuration
access-list 10 permit 192.168.0.0 0.0.255.255
access-list 10 deny   any
!
route-map OSPF-REDIST permit 10
 match ip address 10
 set metric-type type-1
!
router ospf 1
 redistribute eigrp 100 subnets route-map OSPF-REDIST
!

What is the effect of this configuration?

Accepted Answer

Only EIGRP routes in the 192.168.0.0/16 range are redistributed into OSPF as type-1 external routes.. The ACL 10 permits only routes with source IP in the 192.168.0.0/16 range. The route-map OSPF-REDIST matches this ACL and sets the metric type to type-1. Only EIGRP routes that match the ACL (i.e., have a network starting with 192.168.x.x) are redistributed into OSPF as type-1 external routes. Routes not matching the ACL are denied because the route-map has only one permit sequence and the ACL ends with deny any.

Answer

All EIGRP routes are redistributed into OSPF as type-1 external routes.

Answer

EIGRP routes in 192.168.0.0/16 are redistributed as type-2 by default; the set metric-type is ignored.

Answer

The configuration is invalid because the route-map uses an ACL that ends with deny any; a prefix-list must be used instead.

Question 7

Router R4 has the following configuration:

!--- R4 configuration
route-map SETTAG permit 10
 match tag 100
 set tag 200
!
route-map SETTAG permit 20
!
router bgp 65100
 neighbor 10.0.0.1 route-map SETTAG in
!

What is the effect of this configuration?

Accepted Answer

All routes from neighbor 10.0.0.1 are permitted; routes with tag 100 have their tag changed to 200.. The route-map SETTAG has two permit sequences. Sequence 10 matches routes with tag 100 and sets the tag to 200. Sequence 20 is a catch-all permit with no match or set statements. Routes from neighbor 10.0.0.1 that have tag 100 will have their tag changed to 200; all other routes are permitted unchanged. No routes are filtered.

Answer

Routes with tag 100 are denied; all other routes are permitted.

Answer

Only routes with tag 100 are permitted; all other routes are denied.

Answer

The route-map is misconfigured because sequence 20 has no match statement; it should have a match any statement.

Question 8

Consider the following configuration on R5:

!--- R5 configuration
ip prefix-list PL-2 seq 5 permit 10.0.0.0/8 ge 16 le 24
!
route-map RMAP permit 10
 match ip address prefix-list PL-2
 set community 100:100
!
router bgp 65200
 neighbor 192.168.1.2 route-map RMAP out
!

What is the effect of this configuration?

Accepted Answer

Only routes with prefix 10.0.0.0/8 and mask length between 16 and 24 are sent to neighbor with community 100:100.. The prefix-list PL-2 permits prefixes that match 10.0.0.0/8 with a mask length greater than or equal to 16 and less than or equal to 24. So, for example, 10.1.0.0/16, 10.1.1.0/24 are permitted, but 10.0.0.0/8 itself (mask 8) is not. The route-map RMAP sets community 100:100 on matching routes. Routes that do not match the prefix-list are not processed by this route-map (since there is only one sequence), so they are denied (not sent to neighbor).

Answer

All routes with prefix 10.0.0.0/8 are sent to neighbor; routes with mask length between 16 and 24 get community 100:100.

Answer

Routes that match the prefix-list are sent with community 100:100; all other routes are sent without any community.

Answer

The configuration is invalid because the prefix-list uses ge and le together; only one can be used.

Question 9

Examine the following configuration on R6:

!--- R6 configuration
route-map FILTER deny 10
 match tag 50
!
route-map FILTER permit 20
!
router eigrp 200
 distribute-list route-map FILTER in
!

What is the effect of this configuration?

Accepted Answer

All routes with tag 50 are denied; all other routes are permitted.. The distribute-list route-map FILTER in is applied to EIGRP updates received on all interfaces (since no interface is specified). Sequence 10 denies any route with tag 50. Sequence 20 permits all other routes. Therefore, routes with tag 50 are filtered out (not installed in the routing table), while all other routes are accepted.

Answer

Routes with tag 50 are permitted; all other routes are denied.

Answer

The distribute-list is applied only to the first interface; routes with tag 50 are filtered on that interface.

Answer

The configuration is invalid because route-maps cannot be used with distribute-list in EIGRP.

Question 10

What is the default behavior of a route-map when a route does not match any match clause in any sequence?

Accepted Answer

The route is denied by default.. A route-map consists of sequences with permit or deny actions. If a route does not match any match clause in any sequence, it is implicitly denied. This is similar to an access-list: there is an implicit deny at the end of the route-map.

Answer

The route is permitted by default.

Answer

The route is processed by the last sequence regardless of match.

Answer

The route is forwarded to the next route-map if one exists.

Question 11

In BGP, what is the effect of using a route-map with a set community command but without the additive keyword?

Accepted Answer

The existing communities are overwritten by the specified community.. When set community is used without the additive keyword, it replaces any existing community attributes on the route with the specified community. With the additive keyword, the specified community is added to the existing communities.

Answer

The specified community is added to the existing communities.

Answer

The community attribute is not modified; the set command is ignored.

Answer

The route is denied if it already has communities.

Question 12

Which of the following is true regarding the use of prefix-lists versus access-lists for route filtering?

Accepted Answer

Prefix-lists can match on both network address and prefix length, while access-lists match only on network address.. Prefix-lists are designed specifically for route filtering and can match on prefix length using ge and le operators. Access-lists match on source/destination IP and wildcard mask but do not have the ability to specify prefix length ranges. Prefix-lists are more efficient and flexible for route filtering.

Answer

Access-lists can match on prefix length using the 'ge' and 'le' keywords.

Answer

Access-lists are more efficient than prefix-lists for route filtering.

Answer

Prefix-lists can only be used with BGP, while access-lists can be used with any protocol.

Question 13

Which TWO commands can be used to verify the effect of a route-map applied to a BGP neighbor? (Choose TWO.)

Accepted Answer

show ip bgp neighbors x.x.x.x advertised-routes. The commands 'show ip bgp neighbors x.x.x.x advertised-routes' and 'show ip bgp neighbors x.x.x.x routes' directly show the routes being sent or received after route-map filtering. 'show route-map' only displays the route-map definition, not its effect on a specific neighbor. 'show ip bgp' displays the BGP table without neighbor-specific filtering context. 'show ip bgp neighbors' alone does not show the filtered routes.

Answer

show route-map

Answer

show ip bgp

Answer

show ip bgp neighbors x.x.x.x

Question 14

Which TWO statements about route-maps used for route filtering are true? (Choose TWO.)

Accepted Answer

A route-map with a 'deny' statement will drop the route if the match conditions are met.. Route-maps permit or deny routes based on match conditions, and an implicit deny all exists at the end. If no match is found, the route is denied. The sequence number determines the order of evaluation; lower numbers are processed first. The 'continue' clause allows jumping to a different sequence, not the next sequence automatically. A route-map can be used with multiple protocols, but it is not protocol-specific by default.

Answer

The 'continue' clause forces the route-map to evaluate the next sequence number.

Answer

Route-maps can only be applied to BGP neighbors.

Answer

The sequence numbers in a route-map are evaluated in descending order.

Question 15

Which TWO configuration steps are required to filter routes using a prefix-list in a route-map applied to a BGP neighbor? (Choose TWO.)

Accepted Answer

Configure a prefix-list with permit or deny statements for the desired prefixes.. To filter routes, you must define the prefix-list to match the desired prefixes, then create a route-map that uses the prefix-list in a match statement. The route-map is then applied to the BGP neighbor. Defining an access-list is an alternative but not required if using a prefix-list. The 'network' command under BGP is for originating routes, not filtering. The 'distribute-list' command is a separate method and does not use a route-map.

Answer

Define an extended access-list to match the prefixes.

Answer

Apply the route-map to the BGP neighbor using the 'neighbor x.x.x.x route-map' command.

Answer

Use the 'network' command under BGP to advertise the filtered routes.