Pbs.twimg.com CDN problems

dns
media
#1

I’m trying to bring attention to a networking issue I’m experiencing when accessing Twitter from certain networks. I have been told that this issue is Twitter’s problem to address, and have no where else to turn to gain any traction.

Depending on what DNS returns for pbs.twimg.com, the returned address may not be reachable. This causes attempts to display media to fail.

It’s a networking issue, not related to any particular SDK or mobile app.

From my home ISP, nslookup for pbs.twimg.com varies in its response. Sometimes, it will return wildcard.twimg.com and sometimes it will return cs196.wac.edgecastcdn.net. In the cases where it returns wildcard.twimg.com, I cannot load media data, or it loads at a glacial pace, and a traceroute fails.

$ nslookup pbs.twimg.com
Server:10.0.1.1
Address:10.0.1.1#53

Non-authoritative answer:
pbs.twimg.comcanonical name = wildcard.twimg.com.
Name:wildcard.twimg.com
Address: 104.244.46.135

Wait a few minutes, try again, and nslookup returns

$ nslookup pbs.twimg.com
Server:10.0.1.1
Address:10.0.1.1#53

Non-authoritative answer:
pbs.twimg.comcanonical name = cs196.wac.edgecastcdn.net.
cs196.wac.edgecastcdn.netcanonical name = cs2-wac.apr-8315.edgecastdns.net.
cs2-wac.apr-8315.edgecastdns.netcanonical name = cs2-wac-us.8315.ecdns.net.
cs2-wac-us.8315.ecdns.netcanonical name = cs45.wac.edgecastcdn.net.
Name:cs45.wac.edgecastcdn.net
Address: 72.21.91.70

If I get an edgecast CDN address, then things seem to work… That is, until DNS starts returning wildcard.twimg.com again a few minutes later.

I’ve been through the support channel of my ISP, showed them the traceroute, showed them the nslookup results, once they saw that DNS was returning different addresses they said it was out of their hands.

So apparently Twitter’s CDN is misconfigured for at least a certain segment of users/locations. I work as a software developer and everyone that I work with that uses the same ISP (Cox) as me is experiencing the same excruciatingly slow speed when trying to display Twitter media when connected to Cox.

If i just turn off my WiFi and go to LTE then it’s lightning fast, as it used to be. I never get wildcard.twimg.com when doing a lookup over that network.

If someone at Twitter could look into this, bring this to the attention of the appropriate party, or point me in the proper direction to escalate it myself, I’d appreciate it.

#2

Thanks for this detailed report. I cannot commit that we can resolve this very rapidly, but I’ll pass along to see if this is on our radar already. Appreciate it.

#3

Can you please provide the source IP that you’re attempting to route from?

#4

Andy,

The source IP was 68.12.10.24. I have not noticed any major problems since sometime Saturday morning, it has been performing normally, so perhaps the issue has already been addressed.

Thanks for running this up the chain at Twitter! Much appreciated!

Justin

#5

Thanks for this.

#6

Hi Andy,

I just want to report that we were able to reproduce this issue yesterday:

$ nslookup pbs.twimg.com
Server:        207.241.224.9
Address:    207.241.224.9#53

Non-authoritative answer:
pbs.twimg.com    canonical name = cs196.wac.edgecastcdn.net.
cs196.wac.edgecastcdn.net    canonical name = cs2-wac.apr-8315.edgecastdns.net.
cs2-wac.apr-8315.edgecastdns.net    canonical name = cs2-wac-us.8315.ecdns.net.
cs2-wac-us.8315.ecdns.net    canonical name = cs45.wac.edgecastcdn.net.
Name:    cs45.wac.edgecastcdn.net
Address: 72.21.91.70

$ nslookup pbs.twimg.com
Server:        207.241.224.9
Address:    207.241.224.9#53

Non-authoritative answer:
pbs.twimg.com    canonical name = wildcard.twimg.com.
Name:    wildcard.twimg.com
Address: 104.244.46.39
Name:    wildcard.twimg.com
Address: 104.244.46.71

When pbs.twimg.com resolves to wildcard.twimg.com, we don’t see images —we’ve noticed occasionally missing images for a month or so now, and just discovered this thread.

Thanks,

Mary

#7

Hi all!

We were struggling with this issue for at least 2 months and stumbled upon this thread. I think the issue still stands, @jgreenfield, @littleclamator do you have an update about it’s status?

Thank you

#8

Yes The Issue I am also facing the same as I could able to make threads on it twitter api it happen sometimes but still I am facing the problem same

#9

Sorry, we haven’t heard anything from Twitter about the issue.

#10

Given that this thread goes back about 4 months, would it be possible to get a current and clear summary of the issue as it relates to the Twitter developer platform? thank you very much.

#14

Can confirm that issue is still occurring

________________________________________________________________________________

| => date
Tue Jan  2 13:18:37 EST 2018
________________________________________________________________________________

| => nslookup pbs.twimg.com
Server:		192.168.0.1
Address:	192.168.0.1#53

Non-authoritative answer:
pbs.twimg.com	canonical name = wildcard.twimg.com.
Name:	wildcard.twimg.com
Address: 104.244.46.71

One moment later…

________________________________________________________________________________

| => date
Tue Jan  2 13:20:07 EST 2018
________________________________________________________________________________

| => nslookup pbs.twimg.com
Server:		192.168.0.1
Address:	192.168.0.1#53

Non-authoritative answer:
pbs.twimg.com	canonical name = cs196.wac.edgecastcdn.net.
cs196.wac.edgecastcdn.net	canonical name = cs2-wac.apr-8315.edgecastdns.net.
cs2-wac.apr-8315.edgecastdns.net	canonical name = cs2-wac-us.8315.ecdns.net.
cs2-wac-us.8315.ecdns.net	canonical name = cs45.wac.edgecastcdn.net.
Name:	cs45.wac.edgecastcdn.net
Address: 72.21.91.70
#15

Thanks, this looks like a CDN and network issue. We’ll review as folks return from their holidays.

#17

@DominicCabral @littleclamator @Dealhopp we believe that the issues you’re reporting are not related to the one at the start of the thread, although I accept that the symptoms appear similar externally.

Can you please confirm:

  • are you experiencing reachability issues?
  • what external IPs do you see this behaviour from?
  • when did you first notice this?

Much appreciated!

#18

I noticed this problem when I switched from Comcast to AT&T fiber. I have reliable 1Gb internet connection but just using the browser I get a horrible lag from pbs.twimg.com. Could this be an AT&T DNS or routing issue?