Does Comcast run any public/customer-facing NTP servers?
If so, what are their locations and strata?
Certainly, I can use servers on other nets, but it's always nice to have one topologically near and relatively symmetrically consistent.
Thanks for taking the time to reach out to us through our Business Forums. I would love to address your questions regarding NTP servers. Can you please tell me what you would be using them for? -Comcast_Michelle
Thank you for the rapid response, Michelle.
Fair question. I would be pointing my own local NTP server to it/them, and then serving my own network from my server.
Your server(s) will therefore only see queries from my one highest stratum server.
Thank you so much for taking the time to reach back out to us. We do not have NTP servers available for customers use to connect to at this time for this purpose. -Comcast_Michelle
Most - but not all - of the following IP addresses respond to NTP client requests for time or peer connections.
root@ dev ~ # dnsip time.comcast.com
184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199
root@ dev ~ # dnsip time.xfinity.net
root@ dev ~ # dnsip time.xfinity.com
188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 184.108.40.206
They appear to be regionally distributed, so you'll want to look up the IP addresses and find the ones closest to you (wolframalpha is remarkably good at nailing that down).
I'd thought that the time.comcast.net address might be the 'mothership', having 123 as the last octet, same as the NTP port, but not so.
I randomly checked a few as peers, and they all came up as stratum two.