Help Center/ Virtual Private Cloud/ FAQs/ VPCs and Subnets/ Can I Change the CIDR Block of a Subnet?
Updated on 2024-10-25 GMT+08:00
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Can I Change the CIDR Block of a Subnet?

After a subnet is created, the CIDR block cannot be changed.

Properly plan subnet CIDR blocks in advance.
  • The subnet CIDR block size cannot be too small. Ensure that the number of available IP addresses in the subnet meets service requirements. Remember that the first and last three addresses in a subnet CIDR block are reserved for system use. For example, in subnet 10.0.0.0/24, 10.0.0.1 is the gateway address, 10.0.0.253 is the system interface address, 10.0.0.254 is used by DHCP, and 10.0.0.255 is the broadcast address.
  • The subnet CIDR block cannot be too large, either. If you use a CIDR block that is too large, you may not have enough CIDR blocks available later for new subnets, which can be a problem when you want to scale out services.
  • Avoid CIDR block conflicts if you need to connect two VPCs or connect a VPC to an on-premises data center.
Parent topic: VPCs and Subnets