dig gcc.gnu.org succeeds (12.107.209.250), but traceroute gcc.gnu.org fails.

[Matthew Galgoci]

> But traceroute dies:
> 
> traceroute to gcc.gnu.org (12.107.209.250), 64 hops max, 40 byte
> packets
>  1  192.168.1.25 (192.168.1.25)  1.118 ms  1.054 ms  1.034 ms
>  2  c6400-nrp2.xmission.com (166.70.4.75)  54.668 ms  55.107 ms
> 55.658 ms
>  3  c6509-core.xmission.com (166.70.4.76)  53.385 ms  53.144 ms
> 54.938 ms
>  4  gbr1-gi1-0.slc.xmission.com (166.70.4.8)  51.220 ms  52.421 ms
> 51.202 ms
>  5  12.127.106.97 (12.127.106.97)  53.625 ms  55.608 ms  53.101 ms
>  6  gbr3-p30.dvmco.ip.att.net (12.122.2.238)  64.483 ms  64.248 ms
> 63.770 ms
>  7  gbr4-p60.dvmco.ip.att.net (12.122.5.34)  62.244 ms  61.301 ms
> 64.595 ms
>  8  tbr1-p012702.cgcil.ip.att.net (12.122.10.121)  80.338 ms  81.445
> ms  81.805 ms
>  9  tbr1-cl1.n54ny.ip.att.net (12.122.10.1)  99.121 ms  102.996 ms
> 100.798 ms
> 10  tbr2-cl2.n54ny.ip.att.net (12.122.9.130)  100.733 ms  101.833 ms
> 100.343 ms
> 11  tbr2-cl1.wswdc.ip.att.net (12.122.10.54)  110.665 ms  108.933 ms
> 108.957 ms
> 12  gar1-p370.rlgnc.ip.att.net (12.122.3.61)  111.978 ms  110.915 ms
> 112.531 ms
> 13  * * *
> 14  * * *
> 15  * * *
> 16  * * *
> 17  * * *
> 18  * * *

Traceroute icmp is blocked at the last hop you see. This is fairly common 
practice and does not indicate anything in regard to the reachability of
the host. When traceroute works, the only thing that it indicates it the
path across the internet at that _exact_ point in time that you had from 
point A to point B. Traceroutes can also change right out from under you.

-- 
Matthew Galgoci
System Administrator and Sr. Manager of Ruminants
Red Hat, Inc
919.754.3700 x44155