LOC record
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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[edit]
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[edit]
- statdns.net for the coordinates: 52°22′23″N 4°53′32″E / 52.37306°N 4.89222°E
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[edit]
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[edit]
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[edit]
References[edit]
- 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)