CCNA Question of the Week

Which subnet mask would be appropriate for a Class C address used for 9 LANs, each with 12 hosts?

  1. 255.255.255.0
  2. 255.255.255.224
  3. 255.255.255.240
  4. 255.255.255.252

 

The correct answer is 3.

A Class C address default mask is 255.255.255.0; this indicates 8 bits of host. For 9 LANs, 4 subnet bits are required (resulting in a possible 16 LAN subnets). The remaining 4 host bits can address 14 hosts, which is enough to cover the required 12 hosts. Therefore the last octet of the required subnet mask is 11110000; the subnet mask is 255.255.255.240.

References:
For more questions like these, try our CCNA Cert Check

Related Courses:
ICND1 — Interconnecting Cisco Network Devices 1
ICND2 — Interconnecting Cisco Network Devices 2
CCNAX — CCNA Boot Camp v1.1

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