Cisco Cisco Expressway
Appendix 5: NAPTR records
NAPTR records are typically used to specify various methods to connect to a destination URI, for example
by email, by SIP, by H.323. They can also be used to specify the priority to use for those connection types,
for example to use SIP TLS in preference over using SIP TCP or SIP UDP.
by email, by SIP, by H.323. They can also be used to specify the priority to use for those connection types,
for example to use SIP TLS in preference over using SIP TCP or SIP UDP.
NAPTR records are also used in ENUM, when converting a telephone number into a dialable URI. (For
further details on ENUM see
further details on ENUM see
).
NAPTR record format
Example: SIP access to example.com, and for enum lookups for 557120, 557121, and 557122.
$ORIGIN example.com.
IN NAPTR 10 100 "s" "SIPS+D2T" "" _sips._tcp.example.com.
IN NAPTR 12 100 "s" "SIP+D2T" "" _sip._tcp.example.com.
IN NAPTR 14 100 "s" "SIP+D2U" "" _sip._udp.example.com.
$ORIGIN www.example.com.
IN NAPTR 10 100 "s" "http+I2R" "" _http._tcp.example.com.
IN NAPTR 10 100 "s" "ftp+I2R" "" _ftp._tcp.example.com.
$ORIGIN 0.2.1.7.5.5.enum.lookup.com.
IN NAPTR 10 100 "u" "E2U+sip" "!^.*$!john.smith@tandberg.com!" .
IN NAPTR 12 100 "u" "E2U+h323" "!^.*$!john.smith@tandberg.com!" .
IN NAPTR 10 100 "u" "mailto+E2U" "!^.*$!mailto:john.smith@tandberg.com!" .
$ORIGIN 1.2.1.7.5.5.enum.lookup.com.
IN NAPTR 10 100 "u" "E2U+sip" "!^.*$!mary.jones@tandberg.com!" .
$ORIGIN 2.2.1.7.5.5.enum.lookup.com.
IN NAPTR 10 100 "u" "E2U+h323" "!^.*$!peter.archibald@myco.com!" .
IN = Internet routing
NAPTR = record type
10 = order value (use lowest order value first)
100 = preference value if multiple entries have the same order value
"u" = the result is a routable URI
"s" = the result is a DNS SRV record
"a" = the result is an ‘A’or ‘AAAA’ record
"E2U+sip" to make SIP call
"E2U+h323" to make h.323 call
Regular expression:
! = delimiter
"" = no expression used
… usual Regex expressions can be used
Replace field; . = not used
Looking up an ENUM NAPTR record
dig 4.3.7.8.enum4.example.com. NAPTR
Cisco Expressway Cluster Creation and Maintenance Deployment Guide (X8.5)
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Appendix 5: NAPTR records