View source for LOC record

In the [[Domain Name System]], a '''LOC record''' (experimental {{IETF RFC|1876}}) is a means for expressing geographic location information for a [[Domain name|domain name]].

It contains WGS84 [[Earth:Latitude|Latitude]], [[Earth:Longitude|Longitude]] and [[Altitude]] (ellipsoidal height) information together with host/[[Subnetwork|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:

 {{angbr|owner}} {{angbr|TTL}} {{angbr|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:

<pre>
    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)
</pre>

== An example DNS LOC resource record ==

* statdns.net for the [[Earth:Geographic coordinate system|coordinates]]: {{coord|52|22|23|N|4|53|32|E|region:NL_type:landmark|name=StatDNS.net LOC record}}
{{sxhl|
LOC record statdns.net.   IN LOC   52 22 23.000 N 4 53 32.000 E -2.00m 0.00m 10000m 10m
|zone}}

== 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&nbsp;km.  Which is large enough to store the altitude of a circular geosynchronous orbit (i.e. approximately 35,790&nbsp;km above mean sea level).
* Maximum depth of 100&nbsp;km below earth surface (approximated by the [[World Geodetic System#WGS84|WGS84]] [[Earth:Reference ellipsoid|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.:
 $ [[Software:Dig (command)|dig]] loc SW1A2AA.find.me.uk
 {{codett|SW1A2AA.find.me.uk.     2592000 IN      LOC     51 30 12.748 N 0 7 39.612 W 0.00|zone}}

== 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.
* [http://www.ckdhr.com/dns-loc/sites.html Sites supporting DNS LOC]
* {{IETF RFC|1876|link=no}} - How latitude and longitude are stored in a DNS record.
* {{IETF RFC|2426|link=no}} Chapter 3.4.2: Text/directory MIME type GEO
* {{IETF RFC|6350|link=no}} Section 6.5.2: GEO (obsoleted {{IETF RFC|2426|link=no}}, updated by {{IETF RFC|6868|link=no}})

{{DEFAULTSORT:Loc Record}}
[[Category:DNS record types]]

{{Sourceattribution|LOC record}}