DNS & Glossary

NAPTR record (Naming Authority Pointer)

An advanced record that uses regular-expression rules to rewrite a name into a service URI — the backbone of ENUM telephone-number mapping and SIP discovery.

What it stores

A NAPTR record stores order, preference, flags, a service label and a regular-expression rewrite rule. Combined with SRV records, it powers dynamic service discovery in telephony (ENUM, mapping E.164 numbers to SIP URIs).

ZONE FILE
4.3.2.1.e164.arpa. IN NAPTR 100 10 "u" "E2U+sip" "!^.*$!sip:[email protected]!" .

Why it matters

  • It enables flexible, rule-driven mapping from abstract identifiers to concrete services.
  • It is essential to VoIP/ENUM infrastructure.

Common mistakes

  • Errors in the regular-expression rewrite rule that silently break resolution.
  • Using NAPTR where a simpler SRV or CNAME would suffice.

How WebInspect checks this

  • The Network Inspector reports NAPTR records when present in a zone.