IPv6 CIDR contains

ipv6-cidr-contains · version 1.0.0 · URLs & IP addresses · free, no key needed

Test whether one IPv6 CIDR block fully contains another IPv6 CIDR block.

Use when you need to: ipv6 cidr contains · ipv6 subnet contains subnet · check ipv6 cidr containment.

Supported

• ipv6 cidr contains
• ipv6 subnet contains subnet
• check ipv6 cidr containment

Not supported

• IPv4
• partial/overlap-only containment

Behavior

• outer and inner are each address/prefix with host bits zero; otherwise the tool throws.
• contains is true iff every address in inner also lies in outer, i.e. inner.prefix >= outer.prefix and inner's range is a subset of outer's range.
• A CIDR always contains itself (equal blocks yield contains: true).

Input

• outer (string, required): max length 49
• inner (string, required): max length 49

Output

• contains (boolean, required)
• outer_network (string, required): max length 49
• inner_network (string, required): max length 49

Limits

• max cidr length: 49

Example

Request input:

{
  "outer": "2001:db8::/32",
  "inner": "2001:db8:1::/48"
}

Response:

{
  "result": {
    "contains": true,
    "outer_network": "2001:db8::/32",
    "inner_network": "2001:db8:1::/48"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "ipv6-cidr-contains",
  "version": "1.0.0",
  "input": {
    "outer": "2001:db8::/32",
    "inner": "2001:db8:1::/48"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/ipv6-cidr-contains/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"outer":"2001:db8::/32","inner":"2001:db8:1::/48"}'

The machine-readable contract is at /v1/tools/ipv6-cidr-contains/versions/1.0.0.

CLI

node cli.mjs run ipv6-cidr-contains 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• IPv4 CIDR contains: Test whether one IPv4 CIDR block fully contains another IPv4 CIDR block.
• IPv6 CIDR overlap: Test whether two IPv6 CIDR blocks overlap (share at least one address).
• IPv4 CIDR overlap: Test whether two IPv4 CIDR blocks overlap (share at least one address).
• IPv6 CIDR parse: Parse an IPv6 CIDR block into its canonical network address, prefix, first/last address, and total address count.
• IPv6 in CIDR: Test whether an IPv6 address lies in a CIDR prefix whose host bits are zero.
• IPv4 CIDR parse: Parse an IPv4 CIDR block into its network, broadcast, netmask, wildcard mask, usable host range and address counts.