What is the subnet mask if the CIDR is /13?

To determine the subnet mask for a CIDR of /13, we can follow these steps:

1. Understand CIDR notation: CIDR (Classless Inter-Domain Routing) notation is used to represent the network prefix length. It consists of a forward slash (/) followed by a number, which indicates the number of network bits in the subnet mask.

2. Calculate the subnet mask: In CIDR notation, the subnet mask is derived by converting the number after the slash into binary format. In this case, the CIDR is /13, so we need to convert 13 into binary.

   • The binary representation of 13 is 00001101.

3. Determine the subnet mask: The subnet mask is a 32-bit value, where the network bits are represented by 1s and the host bits are represented by 0s. To determine the subnet mask, we need to fill the first 13 bits with 1s and the remaining 19 bits with 0s.

   • The subnet mask for /13 is 11111111.11100000.00000000.00000000 in binary notation.

4. Convert the binary subnet mask to decimal: To make it easier to understand, we can convert the binary subnet mask to decimal format.

   • The decimal representation of the subnet mask for /13 is 255.224.0.0.

Therefore, the subnet mask for a CIDR of /13 is 255.224.0.0.