tcpdumps show a couple of interesting points.1) There are definitely no DNS lookups occurring as a consequence of the Hobbit probes. No port 53 traffic out.
2) The packets from the Hobbit server, and the incoming packets to the Apache server, sometimes look like:
15:20:01.160095 IP (tos 0x0, ttl 62, id 31129, offset 0, flags [DF], proto 6, length: 60) hobbit.45116 > target.http: S [tcp sum ok] 265769416:265769416(0) win 17520 <mss 8760,sackOK,timestamp 143665233 0,nop,wscale 2>
15:20:04.159715 IP (tos 0x0, ttl 62, id 31131, offset 0, flags [DF], proto 6, length: 60) hobbit.45116 > target.http: S [tcp sum ok] 265769416:265769416(0) win 17520 <mss 8760,sackOK,timestamp 143668233 0,nop,wscale 2>
15:20:04.160223 IP (tos 0x0, ttl 62, id 31133, offset 0, flags [DF], proto 6, length: 40) hobbit.45116 > target.http: . [tcp sum ok] 265769417:265769417(0) ack 1051782089 win 17520
So that accounts for three seconds... it appears there are 2 SYN packets, but the first isn't getting processed and there's a 3-second delay to the next SYN (which gets ACKed). I don't know why this happens only with the Hobbit connections... and I don't know why the first SYN seems to be getting ignored. Server is not at all busy.
-Alan Tim McCloskey wrote:
I get that wget/curl always work. Not sure what resolver settings may be implemented differently for hobbit.Still thinking this may be unrelated to hobbit (even though wget/curl work fine for you). We have many apache boxes spanning multiple networks running httpd versions 1.3, 2.0 and 2.2 that hobbit(4.2 with allinone patch) likes just fine and reports accurate times (Seconds: 0.nn). We also have fairly proper forward and reverse DNS records for the systems involved.I can't imagine hobbit parsing the wrong response times, but if that is the case I wonder what external libraries are used (not hobbit provided libs, as ours parse fine and are likely the same as yours).Anyway, good luck with the tcpdump. Regards, Tim Alan Sparks wrote:UseCanonicalName is off, and HostNameLookup is off, on every server, regardless of version.-Alan Tim McCloskey wrote:What do you have for UseCanonicalName in the apache 2.0 boxes?To unsubscribe from the hobbit list, send an e-mail to hobbit-unsubscribe (at) hswn.dk