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.

## Contents

* 1 Record format
* 2 An example DNS LOC resource record
* 3 Altitude for Geosynchronous Earth Satellites
* 4 UK Postcode to DNS LOC record using find.me.uk
* 5 See also
* 6 References

## 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:  [ ⚑ ] 52°22′23″N 4°53′32″E﻿ / ﻿52.37306°N 4.89222°E﻿ / 52.37306; 4.89222﻿ (StatDNS.net LOC record)

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 (approximated by the WGS84 reference ellipsoid).

## UK Postcode to DNS LOC record 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
* ICBM address
* ISO 6709

## References

* 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)

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