An engineer evaluates an operational Cisco router process handling an incoming packet addressed to target host 172.16.35.45. The active IPv4 routing database displays the following entries:
S 172.16.32.0/20 [1/0] via 10.1.1.1
D 172.16.32.0/21 [90/307200] via 10.3.3.3
O 172.16.35.0/26 [110/65] via 10.2.2.2
B 172.16.0.0/16 [20/0] via 10.4.4.4
Which next-hop IP address will be utilized to transmit this traffic?
- 10.2.2.2Cevap
- B10.1.1.1
- C10.3.3.3
- D10.4.4.4
Cevap
10.2.2.2 is selected because the OSPF route 172.16.35.0/26 provides the longest prefix match (/26) for the destination IP address 172.16.35.45.
When a router performs a forwarding lookup for a destination IP address (172.16.35.45), it evaluates all matching prefix entries in the IPv4 routing table. In this case, 172.16.35.45 falls into the network ranges of all four listed prefixes (/16, /20, /21, and /26). According to the Longest Prefix Match principle, the router selects the entry with the highest mask length (/26). Therefore, the packet is forwarded to next-hop 10.2.2.2 associated with 172.16.35.0/26.
Adım Adım Çözüm
Anahtar Kavram
Longest Prefix Match Rule
Tahmini Süre:1m 30s