November 12th, 2015

dotat

LOC records in ac.uk

Since September 1995 we have had a TXT record on cam.ac.uk saying "The University of Cambridge, England". Yesterday I replaced it with a LOC record. The TXT space is getting crowded with things like Google and Microsoft domain authentication tokens and SPF records.

When I rebuilt our DNS servers with automatic failover earlier this year, I used the TXT record for a very basic server health check. I wanted some other ultra-stable record for this purpose which is why I added the LOC record.

What other LOC records are there under ac.uk, I wonder?

Anyone used to be able to AXFR the ac.uk zone but that hasn't been possible for a few years now. But there is a public FOI response containing a list of ac.uk domains from 2011 which is good enough.

A bit of hackery with adns and 20 seconds later I have:

abertay.ac.uk.        LOC 56 46  4.000 N 2 57  5.000 W 50.00m   1m 10000m 10m
cam.ac.uk.            LOC 52 12 19.000 N 0  7  5.000 E 18.00m 10000m 100m 100m
carshalton.ac.uk.     LOC 51 22 17.596 N 0  9 58.698 W 33.00m  10m   100m 10m
marywardcentre.ac.uk. LOC 51 31 15.000 N 0  7 19.000 W  0.00m   1m 10000m 10m
midchesh.ac.uk.       LOC 53 14 58.200 N 2 32 15.190 E 47.00m   1m 10000m 10m
psc.ac.uk.            LOC 51  4 17.000 N 1 19 19.000 W 70.00m 200m   100m 10m
rdg.ac.uk.            LOC 51 26 25.800 N 0 56 46.700 W 87.00m   1m 10000m 10m
reading.ac.uk.        LOC 51 26 25.800 N 0 56 46.700 W 87.00m   1m 10000m 10m
ulcc.ac.uk.           LOC 51 31 16.000 N 0  7 40.000 W 93.00m   1m 10000m 10m
wessexsfc.ac.uk.      LOC 51  4 17.000 N 1 19 19.000 W 70.00m 200m   100m 10m
wilberforce.ac.uk.    LOC 53 46 28.000 N 0 16 42.000 W  0.00m   1m 10000m 10m

A LOC record records latitude, longitude, altitude, diameter, horizontal precision, and vertical precision.

The cam.ac.uk LOC record is supposed to indicate the location of the church of St Mary the Great, which has been the nominal centre of Cambridge since a system of milestones was set up in 1725. The precincts of the University are officially the area within three miles of GSM which corresponds to a diameter a bit less than 10km. The 100m vertical precision is enough to accommodate the 80m chimney at Addenbrookes.

There are a couple of anomalies in the other LOC records.

abertay.ac.uk indicates a random spot in the highlands, not the centre of Dundee as it should.

midchesh.ac.uk should be W not E.

A lot of the records use the default size of 1m diameter and precision of 10km horizontal and 10m vertical.

You can copy and paste the lat/long into Google Maps to see where they land :-)