AT&T Community Forums

Bad routing to Cloudflare DNS for the past few days

I use Cloudflare and Google as my primary and secondary DNS servers for my home network. I noticed that for the past few days, my latency to the Cloudflare DNS is getting progressively worse:

The brown line is Cloudflare. Starting last Sunday night, it has shot up from the about-10 ms it normally shares with the other servers I check, to 17 ms, then to about 27 ms. Tonight it's jumped to over 40 ms. I normally use 1.1.1.1, but a ping of 1.0.0.1 is yielding the same sort of latency.

I figure I'll give it another day or two before I start trying to make some noise. I've seen Cloudflare do this sort of thing before. But usually only a few hours.

[ Be advised that you've posted on a community forum primarily peopled by other customers. I am not an AT&T Employee. An AT&T Customer Support rep may or may not ever reply to your post. ]

Award for Community Excellence Achiever*
*I am not an AT&T employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.

Responses

JefferMC

ACE - Expert

•

36K Messages

2 months ago

It wound back down, so that the extra "third hop" off the baseline followed what looks like a traditional "evening usage" curve. Another thing that I found interesting is shown in these two traceroutes. I can repeat this over and over again, so I think the timing and what it shows is fairly reliable. Note that the IP address on hop 5 is the same in both traceroutes. Note that the latency is worse when going to 1.1.1.1 than 8.8.8.8. Again, this is repeatable... over and over. It must be two different boxes reporting the same IP (must be due to some internal AT&T AnyCast-type nonsense. I hate that crap.)

0

gr8sho

ACE - Professor

•

5.7K Messages

2 months ago

Does anything change if using default DNS?

0

JefferMC

ACE - Expert

•

36K Messages

2 months ago

I don't really follow how my choice of DNS server could affect latency of pings done directly at IP addresses. Ah... to be clear, I am not measuring the latency of the DNS requests, but on PINGs to the DNS servers.

(edited)

0

dave006

Scholar

•

4.2K Messages

2 months ago

It must be two different boxes reporting the same IP (must be due to some internal AT&T AnyCast-type nonsense. I hate that crap.)

Doubtful any network magic happens before you get to 12.240.220.110 since that is the first interface you hit in AS7018 , once there BGP4 routing magic starts to happens to find the best routing to your target addresses of 1.1.1.1 or 8.8.8.8. Both DNS IPs are AnyCast IPs.

ETA: Correct Router IP to 12.240.220.110

Dave

(edited)

0

JefferMC

ACE - Expert

•

36K Messages

2 months ago

Doubtful any network magic happens before you get to 12.240.220.110 since that is the first interface you hit in AS7018

I agree, but I can't come up with any other justification for the "same hop" with the "same IP" returning the TTL-expired errors with consistently different latency based on the destination address on the packet. If it's actually the same router, why is one consistently taking longer than the other. I'll try some other tests.

As I said, 1.1.1.1 has often had periods where it underperforms, ICMP latency-wise, the other DNS servers probably located in Atlanta (I test Verizon (for historical reasons), AT&T, Google and Cloudflare.

(edited)

0