On Sun, Dec 06, 2009 at 02:15:55PM -0500, Celejar wrote: > On Sun, 6 Dec 2009 09:58:12 -0800 > Andrew Sackville-West <andrew@farwestbilliards.com> wrote: > > ... > > > meanwhile, some tests using > > > > time wget http://www.google.com > > ... > > > > real 0m0.279s > > > user 0m0.000s > > > sys 0m0.004s > > > > very consistently. > > > > on the problem machine, this is typical: > > ... > > > > real 0m5.280s > > > user 0m0.000s > > > sys 0m0.004s > > > > the pause is at the "Resolving www.google.com..." line for 5 seconds, > > very consistently. > > > > interestingly this doesn't happen with ping... > > > > and nsloopup www.google.com works just fine as well with something > > like 0.05s real time. > > > > I also see the delay with w3m, which points to the problem being in > > some common http library? Anyway, the delay is consistent at around 5 > > seconds. > > Try some other protocols? An ever better idea: use netcat or telnet to > talk to google.com on port 80 - same server and port, but no client > side HTTP stuff, just plain text going out over the wire. yup, same thing. on the squeeze machine telnet on several ports by name has a five second overhead. telnet by ip address is instantaneous. one a lenny machine, instaneous either way. I did a little digging with tcpdump and some rough timing. Here are typical results on my squeeze machine: andrew@basement:~$ date +%T.%N; telnet www.google.com 80 < /dev/null; date +%T.%N 15:33:19.209029221 Trying 72.14.213.105... Connected to www.l.google.com. Escape character is '^]'. Connection closed by foreign host. 15:33:24.359495441 note the five second lag... relevant tcpdump output (autofill off on purpose to preserve line structure): 15:33:19.211425 IP basement.36071 > cache1.cet.com.domain: 19713+ A? www.google.com. (32) 15:33:19.211440 IP basement.36071 > cache1.cet.com.domain: 21948+ AAAA? www.google.com. (32) 15:33:19.254337 IP cache1.cet.com.domain > basement.36071: 19713 7/4/4 CNAME[|domain] 15:33:24.216053 IP basement.36071 > cache1.cet.com.domain: 19713+ A? www.google.com. (32) 15:33:24.258872 IP cache1.cet.com.domain > basement.36071: 19713 7/4/4 CNAME[|domain] 15:33:24.258902 IP basement.36071 > cache1.cet.com.domain: 21948+ AAAA? www.google.com. (32) 15:33:24.302859 IP cache1.cet.com.domain > basement.36071: 21948 1/1/0 CNAME[|domain] 15:33:24.303090 IP basement.57375 > pv-in-f105.1e100.net.www: Flags [S], seq 3169135473, win 5840, options [mss 1460,sackOK,TS val 755934554 ecr 0,nop,wscale 7], length 0 now I don't really know much about this stuff, but I see that as a DNS exchange with cache1.cet.com which is the name server at 15:33:19.21+... with a quick response and then nothing from my side until 15:33:24.21+ when the request is repeated and then proceeds. compare to the lenny machine: muffy@swfamily:~$ date +%T.%N; telnet www.google.com 80 < /dev/null ; date +%T.%N 15:33:47.058383705 Trying 72.14.213.106... Connected to www.l.google.com. Escape character is '^]'. Connection closed by foreign host. 15:33:47.220861942 15:33:47.061831 IP swfamily.37796 > cache1.cet.com.domain: 10212+ AAAA? www.google.com. (32) 15:33:47.061966 IP swfamily.35621 > cache1.cet.com.domain: 46999+ PTR? 5.224.63.206.in-addr.arpa. (43) 15:33:47.103229 IP cache1.cet.com.domain > swfamily.37796: 10212 1/1/0 CNAME www.l.google.com. (102) 15:33:47.103383 IP swfamily.51262 > cache1.cet.com.domain: 65335+ A? www.google.com. (32) 15:33:47.111645 IP cache1.cet.com.domain > swfamily.35621: 46999 1/2/2 (139) 15:33:47.148277 IP cache1.cet.com.domain > swfamily.51262: 65335 7/4/4 CNAME www.l.google.com.,[|domain] 15:33:47.165497 IP swfamily.37594 > pv-in-f106.1e100.net.www: S 81126028:81126028(0) win 5840 <mss 1460,sackOK,timestamp 222186757 0,nop,wscale 5> there are clearly some differences. the lenny machine is making a AAAA? request (whatever that means) while the squeeze machine is making both a A? and AAAA? requests. And the responses are different. This behavior is consistent across attempts. I'm stumped, frankly. It's out of my depth. A
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