For those that don't know this, if you want to know which cluster you're hitting, you can run:
$ dig o-o.myaddr.l.google.com -t txt +short @8.8.8.8 "172.253.192.142" "edns0-client-subnet x.x.x.0/24"
That will return the ipv4/ipv6 address of the server that handled your request. To get a list of what subnets map to which locations (airport codes), you can run:
$ dig -t TXT +short locations.publicdns.goog. @8.8.8.8 snip... "172.253.192.0/24 cbf ..snip cbf = Council Bluffs, IA