Router R1 has eBGP connections to I1 and I2, routers at the same ISP. The company that
owns R1 can use public address range 130.1.16.0/20. The following output lists all the IP
routes in R1’s routing table within this rangE. Which of the following answers would cause
R1 to advertise the 130.1.16.0/20 prefix to its eBGP peers? (You should assume default
settings for any parameters not mentioned in this question.)
R1# show ip route 130.1.16.0 255.255.240.0 longer-prefixes
! lines omitteD…
O 130.1.16.0/24 [110/3] via 10.5.1.1, 00:14:36, FastEthernet0/1
O 130.1.17.0/24 [110/3] via 10.5.1.1, 00:14:36, FastEthernet0/1
O 130.1.18.0/24 [110/3] via 10.5.1.1, 00:14:36, FastEthernet0/1
A.
Configure R1 with the network 130.1.16.0 mask 255.255.240.0 command.
B.
Configure R1 with the network 130.1.16.0 mask 255.255.240.0 summaryonly command.
C.
Redistribute from OSPF into BGP, filtering so that only routes in the 130.1.16.0/20 range
are redistributed.
D.
Redistribute from OSPF into BGP, filtering so that only routes in the 130.1.16.0/20 range
are redistributed, and create a BGP summary for 130.1.16.0/20.
Explanation:
The network command will take the route from the IP routing table and put the equivalent
into the BGP table, if that exact route exists. The output does not show a route for
130.1.16.0/20, so the network 130.1.16.0 mask 255.255.240.0 command does not match a
specific route. The other answer with a network command is syntactically incorrect.
Redistribution without aggregation would redistribute the three routes, but all three
subordinate routes would be advertised into eBGP. By also using BGP route summarization,
a single route for 130.1.16.0/20 can be advertised.