Classless Inter-Domain Routing. The scheme of freely setting the length of the network part of an IP address as a number of bits (the prefix length) after a slash, as in 192.168.1.0/24, and that notation.
Japanese name: CIDR
CIDR appears in 2 practice questions across 1 topic, including Computer Networking Basics.
Field: Computer Networking Basics
Answer: A. 255.255.240.0
/20 is a mask with the upper 20 bits set to 1. The first 16 bits give 255.255, and the remaining 4 bits fill the upper 4 bits of the third octet. Binary 11110000 is 128 + 64 + 32 + 16 = 240, so the subnet mask is 255.255.240.0. The host part is 12 bits, holding 2^12 − 2 = 4094 hosts. 255.255.255.240 has the upper 28 bits set (/28), and 255.255.248.0 has the upper 21 bits set (/21).
255.255.255.0 has its upper 24 bits set, so in CIDR notation it is written "/24", as in 192.168.1.0/24.
A host has IP address 192.168.1.10 and subnet mask 255.255.…As an Amazon Associate I earn from qualifying purchases.
Subnet mask ARP CSMA/CA Default gateway DHCP DNS (Domain Name System) MAC address NAT (Network Address Translation) OSI reference model Port number