IPv6 Reverse DNS Lookup
IPv6 reverse DNS uses the ip6.arpa zone, with one label for every hex digit of the address. Enter an IPv6 address below.
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Examples:
Reverse DNS Lookup
IPv6 reverse DNS
Zoneip6.arpa
Labels32, one per hex digit, reversed
Example2001:db8::1 → 1.0.0.0…8.b.d.0.1.0.0.2.ip6.arpa
Mail ServersNeed it on IPv6 just as on IPv4
A mail server that sends over IPv6 is checked on its IPv6 address. Gmail is stricter for IPv6 senders, so a missing PTR on IPv6 is a common reason mail fails while IPv4 works.
Providers usually let you set PTR records per address or delegate the reverse zone for your /48 or /64.
Reverse DNS Guides
Questions
Why does my mail fail only over IPv6?
Usually a missing or unconfirmed IPv6 PTR record, or a missing IPv6 address in SPF. Add both, or make the mail server send over IPv4 only.
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