{"uid":"cap_nIDDWnhKHS-QJY_bbMlDe","slug":"network-calc-ipv6-prefix-calculator-b71d06a8","name":"Network Calc IPv6 Prefix Calculator","description":"IPv6 prefix calculator: first and last address, size, number of /64s, the nth subnet, address type and reverse DNS zone.","url":"https://network-calc.x402tookit.com/cidr-ipv6?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["cidr"],"properties":{"cidr":{"type":"string","description":"IPv6 prefix, for example 2001:db8:abcd::/48"},"index":{"type":"string","description":"Zero-based number of the subnet to show (with subnetPrefix, default 0)"},"subnetPrefix":{"type":"integer","description":"Prefix length of subnets to carve (greater 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first/last address, size, /64 count, nth subnet, address type, and reverse DNS zone for an IPv6 CIDR prefix.","exampleAgentPrompt":"What's the first and last address, total size, number of /64 subnets, and reverse DNS zone for the IPv6 prefix 2001:db8:abcd::/48?","exampleUseCases":[{"title":"IPv6 block sizing for ISP allocation","prompt":"I'm about to assign a /48 to a customer — can you tell me the first and last address, how many /64s it contains, and what the reverse DNS zone is for 2001:db8:1234::/48?"},{"title":"Finding the nth subnet in a block","prompt":"I need the 100th /64 subnet (zero-based index 99) carved out of 2001:db8::/32 — what's its CIDR, first address, and last address?"},{"title":"Verifying IPv6 address type","prompt":"Can you check what type of IPv6 address 2001:db8:cafe::/64 is — like whether it's global unicast, link-local, or something else — and also give me its expanded first and last addresses?"}],"resultDescription":"Returns the canonical CIDR, first and last addresses (both compressed and expanded), total address count, number of /64 and /48 subnets, prefix length, netmask, address type classification, reverse DNS zone string, and optionally details of the nth carved subnet including its own first/last addresses and total subnet count.","failureModes":["Invalid IPv6 prefix format returns an error or degraded response","Host bits set in the address (e.g. 2001:db8::1/48) triggers a warning via hostBitsSet flag","subnetPrefix smaller than or equal to the input prefix length returns an error","index out of range for the given subnet carve returns an error or empty subnet object","Non-IPv6 input (e.g. IPv4 CIDR) likely returns an error or unsupported response"],"whenToPreferThis":"Use this endpoint when you need detailed IPv6-specific prefix analysis — especially /64 and /48 subnet counts, address type classification, or reverse DNS zone generation. Prefer this over a generic CIDR comparison or IPv4 subnet tool when working exclusively with IPv6. Ideal for network automation, ISP provisioning, and DNS infrastructure tasks.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:08:13.358Z","isFirstParty":false,"canonicalSlug":"network-calc-ipv6-prefix-calculator-b71d06a8"}