Ceasaigh, I've seen in more then one post about lag you asking about Comcast.. I myself Have comcast and never had an ISSUE until today. do comcast users go through alter.net?
Alter.net is a Verizon Business backbone. There are several routers that our packets travel over (hop) to. alter.net is one of many.
I have done quite a few tracert's tonight and it seems that more than one of Verizon controlled backbones are not "peering" correctly. Our packets are not getting through. Sometimes I can get through one but not another.
The main cause of this is a network outage affecting Verizon fiber customers. I don't know this for sure but based on the tracert's it is the Verizon backbone that is causing the latency/connection issues tonight.
To answer your question not everyone is routed through alter.net so not everyone weill have the issue. Comcast seems to be the main culprit tho.