seq 5 deny 10.1.2.0/24 ge 25 le 27
seq 15 deny 10.2.0.0/16 ge 30 le 30
seq 20 permit 0.0.0.0/0 le 32
A.
R1 will not create/flood a type 3 LSA for subnet 10.1.2.0/26 into area 1.
B.
R1 will not create/flood a Type 3 LSA for subnet 10.1.2.0/24 into area 1.
C.
R1 will not have an OSPF route for subnet 10.1.2.0/26 in its IP routing tablE.
D.
R1 will not have an OSPF route for subnet 10.1.2.0/24 in its IP routing tablE.
Explanation:
When referenced from an area filter-list command, OSPF filters Type 3 LSAs created
on that router, preventing them from being flooded into area 1 (per the configuration
command). As an ABR, R1 would calculate intra-area routes to these area 0
subnets, so this filtering will have no effect on R1’s routes. Sequence number 5 matches
prefixes from 10.1.2.0–10.1.2.255, with prefix lengths between 25–27, and
denies (filters) those prefixes. So, the prefix list will match 10.1.2.0/26 with the first
line, with a deny action. The 10.1.2.0/24 subnet does not match the first line of the
prefix list because the prefix length does not match, but it does match the third line,
the match all line, with a permit action. By matching subnet 10.1.2.0/26 with a deny
action, the filter-list does prevent R1 from flooding a Type 3 LSA for that subnet. By
matching 10.1.2.0/24 with a permit action, R1 does not filter the Type 3 LSA for that
subnet.