They're generally airport codes, so Philadelphia and Amsterdam... unsure about FRE.

The IATA code FRE is assigned to Fera in the Solomon Islands. Freemont Airport does not have an IATA code.

Naming conventions can be inconsistent, and not every datacenter location has an airport. ASD is often used instead of AMS for Amsterdam.

ASD is the IATA code assigned to Andros Town Airport, in the Bahamas. It might also be a commonly used abbreviation for a medical condition.

To answer your 2nd question, yes you can be DDoSd, Azure specifically offers a DDoS protection plan which is quite expensive. https://learn.microsoft.com/en-us/azure/ddos-protection/ddos...

Their topology page has information about PHL/AMS and FRE (seems like Fremont datacenter):

https://web.archive.org/web/20240111132224/https://man.sr.ht...

Linode went through a rather long DDoS attack a few years back with a few of their data enters being offline for a few days, so I would guess yes there.

1. PHL means Philadelphia, AMS means Amsterdam. Yes, just codenames for sites.

2. Depends if DDoS protection is part of the offer, I suppose.