A LOC record gives the physical location of a host or network as latitude, longitude and altitude, with size and precision values.
ckdhr.com. 21600 IN LOC 42 21 43.528 N 71 5 6.284 W -25.00m 1.00m 3000.00m 10.00m
; 42.3621° N, 71.0851° W, altitude -25 m
caida.org. 14400 IN LOC 32 53 1.000 N 117 14 25.000 W 107.00m 30.00m 10.00m 10.00m
; 32.8836° N, 117.2403° W, altitude 107 m
cmu.edu. 21600 IN LOC 40 26 39.000 N 79 56 36.200 W 283.00m 1.00m 10.00m 10.00m
; 40.4442° N, 79.9434° W, altitude 283 m
alink.net. 300 IN LOC 37 22 26.000 N 122 1 47.000 W 30.00m 30.00m 30.00m 10.00m
; 37.3739° N, 122.0297° W, altitude 30 m
LOC records were an experimental way to support tools that map networks. A handful of universities and research networks published them in the 1990s and some still do. Modern IP geolocation services do not read them, so publishing LOC will not change where your visitors appear.
Sizes and precisions are stored in a compact mantissa/exponent form, which is why only values like 1m, 10m or 3000m round-trip exactly.
example.com. 3600 IN LOC 42 21 43.528 N 71 5 6.284 W -25.00m 1m 3000m 10m
; lat lon altitude size horiz-precision vert-precisionWire format: RDATA is 16 octets: version (0), size, horizontal and vertical precision (each 4-bit mantissa, 4-bit exponent, in centimetres), then latitude, longitude (thousandths of an arc-second, offset by 2^31) and altitude (centimetres above a base 100,000 m below the WGS 84 reference spheroid).
| Field | Meaning |
|---|---|
| Latitude / Longitude | Degrees, minutes, seconds and hemisphere (N/S, E/W). |
| Altitude | Metres relative to the WGS 84 spheroid; can be negative. |
| Size | Diameter of a sphere enclosing the entity; default 1m. |
| Horizontal / vertical precision | Accuracy; defaults 10000m and 10m. |