In the Domain Name System

Domain name system

The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...

, a LOC record (RFC 1876) is a means for expressing geographic location information for a domain name.

It contains WGS84 Latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

, Longitude

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 and Altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

 information together with host/subnet

Subnetwork

A subnetwork, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a network into subnetworks is called subnetting....

 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:

   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

• yahoo.com in wiki coordinates: 37°23.5150′N 121°59.3167′W

LOC record yahoo.com.   IN LOC   37 23 30.900 N 121 59 19.000 W 7.00m 100.00m 100.00m 2.00m

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)
  Geo (microformat)
  Geo is a microformat used for marking up WGS84 geographical coordinates in HTML. Although termed a "draft" specification, this is a formality, and the format is stable and in widespread use; not least as a sub-set of the published hCalendar and hCard microformat specifications, neither of which is...
  
  
• Geolocation
  Geolocation
  Geolocation is the identification of the real-world geographic location of an object, such as a radar, mobile phone or an Internet-connected computer terminal...
  
  
• Geolocation API