Multiple choice

Which network command or set of commands will cause OSPF to be enabled for any R1 interface connected to the exhibited subnets?

  1. R1(config-router)# network 10.0.0.0 0.0.0.0 area 0

  2. R1(config-router)# network 10.1.0.0 0.0.0.255 area 0

  3. R1(config-router)# network 10.1.1.0 0.0.0.255 area 0

  4. R1(config-router)# network 10.1.2.4 0.0.0.3 area 0

  5. R1(config-router)# network 10.1.0.0 0.0.0.255.255 area 0
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The OSPF 'network' command uses a wildcard mask (inverse of subnet mask) to match interfaces. The command 'network 10.1.0.0 0.0.0.255 area 0' means 'match any interface with an IP in the 10.1.x.x range where the third octet can vary (0-255)'. This enables OSPF on all interfaces whose IP addresses fall within 10.1.0.0/16 networks with /24 subnets. Option A's 0.0.0.0 wildcard would only match 10.0.0.0/32 (a single host), option C is too specific, option D uses point-to-point mask, and option E has an invalid wildcard mask (four octets instead of three).

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