LOC record

In the Domain Name System, a LOC record (experimental RFC 1876) is a means for expressing geographic location information for a domain name.

It contains WGS84 Latitude, Longitude and Altitude (ellipsoidal height) information together with host/subnet physical size and location accuracy. This information can be queried by other computers connected to the Internet.

Record format

The LOC record is expressed in a master file in the following format:

<owner> <TTL> <class> LOC d1 [m1 [s1]] {"N"|"S"}  d2 [m2 [s2]] {"E"|"W"}
                          alt["m"] [siz["m"]     [hp["m"] [vp["m"]]]]
(The parentheses are used for multi-line data as specified in [RFC 1035] section 5.1.)
where: d1:     [0 .. 90]            (degrees latitude)
       d2:     [0 .. 180]           (degrees longitude)
       m1, m2: [0 .. 59]            (minutes latitude/longitude)
       s1, s2: [0 .. 59.999]        (seconds latitude/longitude)
       alt:    [-100000.00 .. 42849672.95] BY .01 (altitude in meters)
       siz, hp, vp: [0 .. 90000000.00] (size/precision in meters)

An example DNS LOC resource record

• statdns.net for the coordinates:

LOC record statdns.net.   IN LOC   52 22 23.000 N 4 53 32.000 E -2.00m 0.00m 10000m 10m

Altitude for Geosynchronous Earth Satellites

The altitude range provides the following:

• DNS altitude range [-100000.00 .. 42849672.95]. This range can be easily stored in 4 bytes.
• Maximum altitude is 42,849.67295 km. Which is large enough to store the altitude of a circular geosynchronous orbit (i.e. approximately 35,790 km above mean sea level).
• Maximum depth of 100 km below earth surface.

Postcode to LOC in DNS using find.me.uk

You can look up the LOC record for any UK postcode, e.g.:

$ dig loc SW1A2AA.find.me.uk
SW1A2AA.find.me.uk.     2592000 IN      LOC     51 30 12.748 N 0 7 39.612 W 0.00

See also

• List of DNS record types
• Geo (microformat)
• Geolocation
• Geolocation API

References

• Lookup GPS coordinates in DNS - LOC lookup (Broken as of 2016-05-18)
• GeoTrace - Map a hostname or domain with a DNS LOC record
• DNS-LOC calculator for djbdns's tinydns
• Wikipedia:WikiProject Geographical coordinates The Wikipedia location resource.
• Sites supporting DNS LOC
• RFC 1876 - How latitude and longitude are stored in a DNS record.
• RFC 2426 Chapter 3.4.2: Text/directory MIME type GEO
• RFC 6350 Section 6.5.2: GEO (obsoleted RFC 2426, updated by RFC 6868)