4

For weeks now, I have been seeing this error often:

[Error] Failed to load resource: A server with the specified hostname could not be found. (https://cdn.sstatic.net/stackoverflow/[foo.css | bar.js | etc])

Basically stack overflow loads with no CSS or JavaScript. After a couple of minutes the problem goes away.

It happens multiple times per day, and has been going on for weeks. I'm using Safari on a Mac and live in Australia. My ISP is Internode, we have a business plan which should be very stable - they're the most reliable ISP available in my city.

Haven't had any issues like this with any other website, if the problem's on my end then it must be on my Mac and nothing to do with my network connection.


Ping output:

$ ping cdn.sstatic.net
PING sstatic.net.cdn.cloudflare.net (141.101.114.59): 56 data bytes
64 bytes from 141.101.114.59: icmp_seq=0 ttl=58 time=53.258 ms
64 bytes from 141.101.114.59: icmp_seq=1 ttl=58 time=52.086 ms
64 bytes from 141.101.114.59: icmp_seq=2 ttl=58 time=66.725 ms

More debugging info:

For future reference: Here's a list of things that can help the support people at the CDN to debug issues like this:

Sample CDN file (that is having issues), e.g. http://cdn.sstatic.net/rpg/all.css?v=c9c55a2b82c5

Since it's working right now, I just get a big css file from that URL.

Your IP address

IP is 150.101.176.66 - it's static, so would have been the same the other day.

A traceroute to the CDN, i.e. sstatic.stackexchange.netdna-cdn.com

traceroute to sn.sstatic.stackexchange.netdna-cdn.com (119.81.42.202), 64 hops max, 52 byte packets
 1  192.168.99.250 (192.168.99.250)  0.522 ms  0.312 ms  1.067 ms
 2  59.167.221.41 (59.167.221.41)  1.707 ms  2.732 ms  1.304 ms
 3  lns20.bne1.on.ii.net (150.101.180.24)  40.753 ms  40.976 ms  41.920 ms
 4  xe-0-1-1.cr1.bne7.on.ii.net (150.101.33.136)  43.018 ms  43.162 ms  75.065 ms
 5  ae0.cr1.bne4.on.ii.net (150.101.33.4)  41.017 ms  43.393 ms  40.160 ms
 6  ae1.br1.syd4.on.ii.net (150.101.33.18)  57.427 ms  57.589 ms  57.445 ms
 7  ae3.cr1.mel8.on.ii.net (150.101.33.27)  79.864 ms  67.294 ms  70.458 ms
 8  ae0.cr1.mel4.on.ii.net (150.101.33.10)  71.664 ms  67.231 ms  66.688 ms
 9  ae1.cr1.adl2.on.ii.net (150.101.33.41)  76.603 ms  74.279 ms  75.087 ms
10  ae2.cr1.per2.on.ii.net (150.101.33.39)  107.704 ms  135.812 ms  105.969 ms
11  ae0.cr1.per1.on.ii.net (150.101.33.12)  108.398 ms  106.283 ms  103.026 ms
12  te0-3-0.cor1.per1.on.ii.net (150.101.33.99)  194.914 ms *  153.275 ms
13  36351.sgw.equinix.com (202.79.197.69)  155.768 ms  153.179 ms
    po0-3-0.bdr1.sin1.on.ii.net (203.16.211.229)  151.881 ms
14  36351.sgw.equinix.com (202.79.197.69)  150.048 ms
    ae5.dar01.sr03.sng01.networklayer.com (50.97.18.197)  151.780 ms  152.575 ms
15  po2.fcr01.sr03.sng01.networklayer.com (174.133.118.133)  155.465 ms
    ae5.dar01.sr03.sng01.networklayer.com (50.97.18.197)  152.160 ms *
16  po2.fcr01.sr03.sng01.networklayer.com (174.133.118.133)  160.383 ms
    119.81.42.202-static.reverse.softlayer.com (119.81.42.202)  150.726 ms  153.432 ms

A traceroute to the Origin, that is sstatic.net

traceroute to sstatic.net (198.252.206.16), 64 hops max, 52 byte packets
 1  192.168.99.250 (192.168.99.250)  0.486 ms  0.664 ms  1.140 ms
 2  eth59-167-221-41.qld.adsl.internode.on.net (59.167.221.41)  2.382 ms  1.021 ms  1.019 ms
 3  lns20.bne1.on.ii.net (150.101.180.24)  41.668 ms  39.862 ms  44.868 ms
 4  xe-0-1-1.cr1.bne7.on.ii.net (150.101.33.136)  50.312 ms  40.522 ms  40.617 ms
 5  ae0.cr1.bne4.on.ii.net (150.101.33.4)  43.592 ms  41.395 ms  40.627 ms
 6  ae1.br1.syd4.on.ii.net (150.101.33.18)  58.200 ms  62.051 ms  68.964 ms
 7  te0-1-1-2.bd1.lax1.on.ii.net (203.16.213.65)  235.217 ms  246.080 ms
    te0-0-0-1.br1.lax1.on.ii.net (203.16.213.69)  203.886 ms
 8  sl-st30-la-.sprintlink.net (144.223.30.1)  202.476 ms  203.309 ms  204.556 ms
 9  sl-crs2-ana-0-15-0-0.sprintlink.net (144.232.19.226)  235.924 ms
    144.232.1.177 (144.232.1.177)  205.823 ms
    sl-crs2-ana-0-15-0-0.sprintlink.net (144.232.19.226)  238.687 ms
10  144.232.7.165 (144.232.7.165)  215.392 ms  214.001 ms
    144.232.25.79 (144.232.25.79)  213.309 ms
11  144.232.7.140 (144.232.7.140)  244.666 ms
    144.232.7.142 (144.232.7.142)  245.011 ms
    144.232.7.140 (144.232.7.140)  242.533 ms
12  sl-tisca1-369951-0.sprintlink.net (144.228.111.22)  238.641 ms  237.119 ms  238.981 ms
13  xe-11-0-1.nyc32.ip4.tinet.net (141.136.110.186)  295.844 ms
    xe-11-1-1.nyc32.ip4.tinet.net (141.136.110.190)  291.539 ms
    xe-11-0-1.nyc32.ip4.tinet.net (141.136.110.186)  321.210 ms
14  internap-gw.ip4.tinet.net (216.221.159.206)  292.898 ms  282.914 ms
    internap-gw.ip4.tinet.net (216.221.159.218)  303.924 ms
15  border1.po2-20g-bbnet2.nym008.pnap.net (216.52.95.65)  289.369 ms  281.150 ms  292.216 ms
16  stackexchange-1.border1.nym008.pnap.net (74.201.252.22)  290.153 ms  280.855 ms  289.902 ms
17  stackoverflow.com (198.252.206.16)  283.255 ms  282.204 ms  290.090 ms

Which datacenter you are hitting (go to http://debug-02.netdna-cdn.com/, it will tell you "You are hitting the NetDNA XYZ Datacenter")

I get this: NetDNA San Francisco Datacenter — why is that? cdn.sstatic.net 60ms away when I ping it (just like it was yesterday). San Francisco should be 200 or 300ms.

  • If you run, ping cdn.sstatic.net, what does it output? – Cole Johnson Jul 30 '13 at 2:14
  • @ColeJohnson I have edited my question with the output. That latency from here means it's an Australian datacenter. Likely in sydney/canberra/melbourne. – Abhi Beckert Jul 30 '13 at 7:00
  • I've also been experiencing long loading times, the issue never lasts very long. Living in Belgium. Ping and tracert both output latencies below 10ms when the CDN is loading fine. – Stijn Jul 30 '13 at 7:36
  • 1
    Maybe the steps from Problems with CDN DNS can get some more info? And are you on IPv6? (When in doubt, see ipv6-test.com. IPv6 works fine for me, from Amsterdam, and others though.) See also the information the team likes to receive. – Arjan Jul 30 '13 at 8:05
  • The fact that the ping works but loading doesn't confuses me. – Cole Johnson Jul 30 '13 at 19:04
  • 1
    @ColeJohnson the server is available almost always. But once or twice a day it stops working for a few minutes. – Abhi Beckert Jul 31 '13 at 10:01
  • @Arjan my ISP requires manually enabling IPv6 and I just tested, it has not been enabled for my connection. – Abhi Beckert Jul 31 '13 at 10:12
  • @Arjan I've added the extra details from your "the information the team likes to receive" link. – Abhi Beckert Jul 31 '13 at 10:21
  • Is this still an issue? The CDN is temporarily not using HTTPS anymore. – Arjan Aug 3 '13 at 21:00
  • @Arjan I'm not sure yet, it hasn't happened the last couple days but I haven't been working for 3 days. – Abhi Beckert Aug 4 '13 at 22:29
  • @Arjan I haven't had any more problems. – Abhi Beckert Aug 7 '13 at 5:10
  • @Arjan this problem has returned the last few days. Server not found for cdn.sstatic.net. It's not using https. – Abhi Beckert Aug 21 '13 at 22:50
  • I guess it's better to contact the team and ask what details they need to help debugging. Refer to this question, make sure to tell them you're not on IPv6 and that the earlier HTTPS change helped, and ask if meta.stackexchange.com/questions/97663/… is still up to date? (It's not.) – Arjan Aug 22 '13 at 7:59

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