CIDR 

• Classless Inter-Domain Routing

• 1993: replaces classful addressing (A, B, C) with VLSM

• RFC's 1517 to 1520

• familiar slash notation

• Assigned by Internet Assigned Numbers Authority (IANA), Regional Internet Registries (APNIC), then ISPs

210.8.138.0/24
210.48.160.0/20
210.54.192.0/18
210.55.140.0/24
210.55.160.0/20
210.55.184.0/21
203.110.0.0/18
210.55.192.0/21
210.55.202.0/23
203.144.32.0/20
203.152.96.0/19
203.161.39.0/24