Elastic Compute Service:Prefix lists

Term

Description

maximum number of entries

The maximum number of entries in a prefix list. An entry consists of a CIDR block and an optional description.

address family

The address family of the entries in a prefix list. Supported values are IPv4 and IPv6. All entries in a prefix list must belong to the same address family.

CIDR block

Classless Inter-Domain Routing (CIDR) is an IP addressing method that allocates IP addresses more efficiently than the traditional Class A, B, and C models. CIDR uses slash notation: IP address/number of bits in the network ID.

• Example 1: Convert a CIDR block to an IP address range

  Take 10.0.0.0/8 as an example. Its 32-bit binary representation is 00001010.00000000.00000000.00000000. The /8 indicates an 8-bit network ID, which means the first 8 bits are fixed. This corresponds to a network range from 00001010.00000000.00000000.00000000 to 00001010.11111111.11111111.11111111. In decimal notation, 10.0.0.0/8 represents the IP address range from 10.0.0.0 to 10.255.255.255 with a subnet mask of 255.0.0.0.

• Example 2: Convert an IP address range to a CIDR block

  Take the IP address range 192.168.0.0 to 192.168.31.255 as an example. The binary representation of the last two octets ranges from 00000000.00000000 to 00011111.11111111. This shows that the first 19 bits (8*2 + 3) are fixed. Therefore, the CIDR block is 192.168.0.0/19.

associated resource

A resource that references a prefix list.

Item

Limit

Increase method

Maximum number of prefix lists per Alibaba Cloud account in a region

100

Not supported

Maximum number of entries per prefix list

200

Not supported

Maximum number of resources that can be associated with a prefix list

1,000

Not supported