Rock wrote:
> What can I do to UNDERSTAND why, periodically, I can't reach
> www.centos.org (but everyone else can)?
>
> Every few months, http://www.centos.org just drops off for me
> and for me only. It's not the web site, because I can reach it
> via a proxy (e.g., TOR browser bundle) and other tests show it
> to be alive (e.g., http://www.downforeveryoneorjustme.com/centos.org
> or http://traceroute.monitis.com).
>
> But, for me, I just can't reach it by any means.
Could you define "me"? Are you using this at home, or at work? What kind
of connection? If this is work, are you paying for a fix IP?
>
> Mike Easter kindly determined "centos.org does not echo ICMP or UDP
> pings, only TCP, and its associated netblock level3 doesn't echo UDP,
> but does echo ICMP and TCP."
>
> But, for me, this is what a traceroute returned just now on Centos:
>
> $ traceroute www.centos.org
> ... early hops removed ...
> 16 ae-6-6.ebr2.LosAngeles1.Level3.net (4.69.148.201) 211.850 ms
> ae-3-3.ebr3.Dallas1.Level3.net (4.69.132.78) 205.221 ms
> ae-6-6.ebr2.LosAngeles1.Level3.net (4.69.148.201) 207.392 ms
> 17 ae-3-3.ebr3.Dallas1.Level3.net (4.69.132.78) 128.453 ms
> ae-73-73.csw2.Dallas1.Level3.net (4.69.151.145) 160.451 ms
> ae-93-93.csw4.Dallas1.Level3.net (4.69.151.169) 160.437 ms
> 18 ae-83-83.csw3.Dallas1.Level3.net (4.69.151.157) 165.923 ms
> ae-1-60.edge3.Dallas1.Level3.net (4.69.145.8) 165.920 ms 178.414 ms
> 19 LAYERED-TEC.edge3.Dallas1.Level3.net (4.71.170.6) 241.537 ms 244.324
> ms ae-3-80.edge3.Dallas1.Level3.net (4.69.145.136) 244.318 ms
> 20 * LAYERED-TEC.edge3.Dallas1.Level3.net (4.71.170.6) 244.291 ms
> 244.250 ms
Interesting. I get to 20 (except for me it's 15), and www.centos.org is
the next hop (16). Now, I *do* have fat pipes and good connections (this
is a US fed gov't site), but still....
<snip>
> My related questions are:
> 1. What can I do (on Centos) to UNDERSTAND this problem?
> 2. Why does this problem happen every few months to me (and to just me)?
> 3. How can the net be this arbitrary and still work?
Have you spoken to your ISP? When you try the traceroute, and it fails,
have you tried other well-known locations, like google.com, or
slashdot.org?
Also, have you compared the contents of /etc/resolv.conf now, and again
when centos.org isn't visible?
Sounds like either a firewall, spam, or nameserver issue.
mark
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