Naming major city ISP POPs by IATA airport codes is a practice that goes back to uunet/AS701 in about 1995, maybe a bit earlier, when talking about reverse DNS for public IP space. It actually predates the existence of ARIN, even.
then appending a number, so your first POP/core site in the DFW area might be DFW01, then DFW02, DFW03, and so on.
On an international scale another non-airport or IATA related method is to group by ISO standard two or three country codes and then state/province/regional internal subdivision two letter abbreviations, so something in the bay area of california might have the last part of its DNS name as sfo01.ca.us.as12345.net
I prefer using the [United Nations Code for Trade and Transport Locations](http://www.unece.org/cefact/locode/service/location.html) (UN/LOCODE) value based on the address of the host's data center. It covers more specific locations than something like the IATA airport codes, and is still a well defined standard.
Most ISPs will usually use the icann standard two letter ccTLD for the country where the pop is, which is usually similar to what you linked, but not always.
From my understanding it's more of a "what's the most well known airport". Google LA is in Venice, so it's closest airport should be SMO, it's still referred to in corp speak and machine naming as LAX.
The point of naming convention isnt to be painfully pedantically correct, like this comment. It's to provide a useful guidepost to humans, who know LAX but don't know about SMO.
Why didn't you mention ICAO codes, they'd be more universally correct anyways, right? KSMO, KLAX?
then appending a number, so your first POP/core site in the DFW area might be DFW01, then DFW02, DFW03, and so on.
On an international scale another non-airport or IATA related method is to group by ISO standard two or three country codes and then state/province/regional internal subdivision two letter abbreviations, so something in the bay area of california might have the last part of its DNS name as sfo01.ca.us.as12345.net