IPv6 Nibble Boundary & Reverse DNS Planner
Analyze IPv6 reverse DNS delegations on 4-bit nibble boundaries. Calculate ip6.arpa reverse DNS zones, visualize prefix splits, and generate PTR DNS templates.
Understanding IPv6 Nibble Boundaries & Reverse DNS
In IPv6 reverse DNS delegation, IP addresses are expanded into 32 hexadecimal digits separated by dots under the ip6.arpa domain hierarchy. Because each hexadecimal character represents 4 bits (a nibble), standard DNS zone delegations occur cleanly on multiples of 4 bits (e.g. /32, /48, /56, /64).
Why Nibble Boundaries Matter
Delegating a reverse DNS zone that does not align to a 4-bit boundary (such as /50 or /60) requires non-standard classless DNS delegation hacks. Aligning IPv6 allocations to /48, /56, or /64 boundaries allows straightforward zone delegation to authoritative nameservers without complex CNAME/NS record layering.
Relevant Standards
Reverse IPv6 DNS delegations follow RFC 3596 (DNS Extensions to Support IP Version 6) and RFC 8501 (Reverse DNS in IPv6 for Internet Service Providers).