NAPTR record
A NAPTR (naming authority pointer) record holds a rule for turning one string into another: a phone number into a SIP address (ENUM), or a domain into the right SRV record for a protocol. Phone systems and mobile networks are the main users.
| Record type | NAPTR |
|---|---|
| Type number | 35 |
| Used for | Services |
| How common | Specialist |
| Defined in | RFC 3403, RFC 6116 |
Format
<name> <ttl> IN NAPTR <order> <preference> "<flags>" "<service>" "<regexp>" <replacement>
| Field | What it means | Accepted values |
|---|---|---|
| Order | Rules are processed lowest first. | 0 to 65535. |
| Preference | Among equal orders, lower is preferred. | 0 to 65535. |
| Flags | What to do next: S (look up SRV), A (look up an address), U (the result is a URI), P (protocol-specific), or empty (another NAPTR). | "S", "A", "U", "P", "" |
| Service | The service and protocol. | Such as "E2U+sip" or "SIP+D2T". |
| Regexp | A substitution applied to the input, for U rules. | "!^.*$!sip:info@example.com!", or empty. |
| Replacement | The next name to look up, for S and A rules. . when the regexp is used. | A host name or .. |
Check an NAPTR record
Type or paste a record in zone-file form (name, TTL, type, value) or just its value. Each part is explained as you type.
A valid NAPTR record.
| Part | What it means |
|---|---|
| Nameexample.com. | A full name: the final dot means nothing is added to it. |
| TTL3600 | Resolvers may keep this answer for 1 hour before asking again. Changes can take that long to reach everyone. |
| ClassIN | Internet. Every record you'll write uses IN. |
| TypeNAPTR | Rewrite rules, used by phone systems (ENUM, SIP). |
| Order10 | Rules are processed lowest order first. |
| Preference100 | Among rules with the same order, lower preference is tried first. |
| Flags"S" | S: the next lookup is an SRV record. |
| Service"SIP+D2T" | The service and protocol this rule is for, such as E2U+sip or SIP+D2T. |
| Regexp"" | A substitution applied to the original string, used with the U flag. Empty when the replacement is used. |
| Replacement_sip._tcp.example.com. | The replacement: a host name. |
Examples
SIP over TCP
example.com. 3600 IN NAPTR 10 100 "S" "SIP+D2T" "" _sip._tcp.example.com.
SIP clients learn to use TCP and look up the SRV record.
ENUM phone number
4.3.2.1.5.5.5.0.0.8.1.e164.arpa. 3600 IN NAPTR 100 10 "U" "E2U+sip" "!^.*$!sip:info@example.com!" .
+1 800 555 1234 maps to a SIP address.
Look up NAPTR records
TTL
3600. How TTL works
Common mistakes
- Quoting the replacement or leaving the flags unquoted.
- Using both a regexp and a replacement in one rule; only one applies.
At your DNS host
- Cloudflare, Route 53 and Google Cloud DNS support NAPTR. Most registrar panels don't.
Questions
Do I need NAPTR records?
Only if a VoIP or telecom provider asks for them. Websites and email never use them.
This page is also available as Markdown.
Lemon Domains keeps every domain you own in one place, with expiry reminders, change monitoring and DNS editing from your AI assistant. Get started free