Which CIDR notation corresponds to the private IPv4 block 172.16.0.0?

Which CIDR notation corresponds to the private IPv4 block 172.16.0.0?

• A. /16
• B. /12
• C. /8
• D. /24

Answer: (B)

CIDR notation defines how many leading bits are fixed for the network portion. The private block that starts at 172.16.0.0 uses a /12 prefix, so the network is 172.16.0.0/12. This covers addresses from 172.16.0.0 up to 172.31.255.255, with a corresponding mask of 255.240.0.0. The other options would create smaller or larger ranges: /16 would stop at 172.16.255.255, /8 would include 172.0.0.0 through 172.255.255.255, and /24 would cover only 172.16.0.0 through 172.16.0.255. Thus, /12 is the correct CIDR for the 172.16.0.0 private block.

CIDR notation defines how many leading bits are fixed for the network portion. The private block that starts at 172.16.0.0 uses a /12 prefix, so the network is 172.16.0.0/12. This covers addresses from 172.16.0.0 up to 172.31.255.255, with a corresponding mask of 255.240.0.0. The other options would create smaller or larger ranges: /16 would stop at 172.16.255.255, /8 would include 172.0.0.0 through 172.255.255.255, and /24 would cover only 172.16.0.0 through 172.16.0.255. Thus, /12 is the correct CIDR for the 172.16.0.0 private block.