[Unbound-users] Long recursion times

[Pete]

Hi,

I was wondering if anyone can help me picture what sort of scenario
could result in hour-long recursion times. For example,


[1224870602] unbound[22560:0] info: server stats for thread 0: 1376
queries, 108 answers from cache, 1268 recursions
[1224870602] unbound[22560:0] info: server stats for thread 0:
requestlist max 55 avg 23.2926 exceeded 0
[1224870602] unbound[22560:0] info: average recursion processing time
58.964890 sec
[1224870602] unbound[22560:0] info: histogram of recursion processing times
[1224870602] unbound[22560:0] info: [25%]=0.0458265 median[50%]=0.116073
[75%]=0.237329
[1224870602] unbound[22560:0] info: lower(secs) upper(secs) recursions
[1224870602] unbound[22560:0] info:    0.000000    0.000001 79
[1224870602] unbound[22560:0] info:    0.004096    0.008192 2
[1224870602] unbound[22560:0] info:    0.016384    0.032768 56
[1224870602] unbound[22560:0] info:    0.032768    0.065536 34
[1224870602] unbound[22560:0] info:    0.065536    0.131072 202
[1224870602] unbound[22560:0] info:    0.131072    0.262144 284
[1224870602] unbound[22560:0] info:    0.262144    0.524288 309
[1224870602] unbound[22560:0] info:    0.524288    1.000000 69
[1224870602] unbound[22560:0] info:    1.000000    2.000000 17
[1224870602] unbound[22560:0] info:    2.000000    4.000000 7
[1224870602] unbound[22560:0] info:    4.000000    8.000000 7
[1224870602] unbound[22560:0] info:    8.000000   16.000000 5
[1224870602] unbound[22560:0] info:   16.000000   32.000000 7
[1224870602] unbound[22560:0] info:   32.000000   64.000000 8
[1224870602] unbound[22560:0] info:   64.000000  128.000000 64
[1224870602] unbound[22560:0] info:  128.000000  256.000000 53
[1224870602] unbound[22560:0] info:  256.000000  512.000000 9
[1224870602] unbound[22560:0] info:  512.000000 1024.000000 16
[1224870602] unbound[22560:0] info: 1024.000000 2048.000000 14
[1224870602] unbound[22560:0] info: 2048.000000 4096.000000 7


As you can see by the last few lines, some queries are taking a *long* time.

I run unbound on several low-traffic resolvers, all of them configured
the same, but I see times greater than 256 secs only on one of them.

I'm having trouble imagining how a query could last an hour. Just trying
to get a big-picture idea of what might be going on. Any thoughts?