resolver change?

Volodymyr Kostyrko c.kworr at gmail.com
Mon Jan 28 01:10:07 PST 2008


Dag-Erling Smørgrav пишет:
> Did something change in our resolver / getaddrinfo() recently?  Check
> this out:
> 
> des at soe ~% cat /etc/ntp.conf
> server europe.pool.ntp.org iburst
> server europe.pool.ntp.org iburst
> server europe.pool.ntp.org iburst
> server europe.pool.ntp.org iburst
> server europe.pool.ntp.org iburst
> server europe.pool.ntp.org iburst
> des at soe ~% ntpq -pn
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  81.169.180.26   .INIT.          16 u    -  512    0    0.000    0.000 4000..00
>  81.169.180.26   .INIT.          16 u    -  512    0    0.000    0.000 4000..00
>  81.169.180.26   .INIT.          16 u    -  512    0    0.000    0.000 4000..00
>  81.169.180.26   .INIT.          16 u    -  512    0    0.000    0.000 4000..00
>  81.169.180.26   .INIT.          16 u    -  512    0    0.000    0.000 4000..00
> *81.169.180.26   192.53.103.104   2 u    2   64   77   63.218  -19.045   3.331
> 
> europe.pool.ntp.org returns a different address every time you query it,
> and this used to work correctly.  I don't know when it changed; it
> worked fine before I last rebooted my NTP server five days ago, but its
> userland is from December 16.
> 
> It is *not* a name server issue:
> 
> des at soe ~% host europe.pool.ntp.org
> europe.pool.ntp.org has address 81.169.180.26
> europe.pool.ntp.org has address 77.66.32.156
> europe.pool.ntp.org has address 217.8.241.75
> europe.pool.ntp.org has address 130.226.232.145
> europe.pool.ntp.org has address 87.32.0.19
> des at soe ~% host europe.pool.ntp.org
> europe.pool.ntp.org has address 87.32.0.19
> europe.pool.ntp.org has address 81.169.180.26
> europe.pool.ntp.org has address 77.66.32.156
> europe.pool.ntp.org has address 217.8.241.75
> europe.pool.ntp.org has address 130.226.232.145
> 
> Somehow, ntpd (or libc) is caching the result of the lookup where it
> previously didn't.
> 
> But this doesn't make sense, since neither ntpd nor libc nor
> /etc/{nsswitch,ntp,resolv}.conf have changed since it last worked.
> 
> For now, I'm going to work around it by explicitly using
> [1-3].europe.pool.ntp.org, but I'd really like to know what's going
> on...
> 
> DES

Well, tried that and found that if you rapidly issue a host command the 
results still the same (for 1 or 2 secs).

 > host 3.europe.pool.ntp.org
3.europe.pool.ntp.org has address 212.13.207.101
3.europe.pool.ntp.org has address 87.229.78.162
3.europe.pool.ntp.org has address 193.228.143.13
3.europe.pool.ntp.org has address 192.108.114.23
3.europe.pool.ntp.org has address 194.238.48.3
 > host 3.europe.pool.ntp.org
3.europe.pool.ntp.org has address 212.13.207.101
3.europe.pool.ntp.org has address 87.229.78.162
3.europe.pool.ntp.org has address 193.228.143.13
3.europe.pool.ntp.org has address 192.108.114.23
3.europe.pool.ntp.org has address 194.238.48.3
 > host 3.europe.pool.ntp.org
3.europe.pool.ntp.org has address 87.229.78.162
3.europe.pool.ntp.org has address 193.228.143.13
3.europe.pool.ntp.org has address 192.108.114.23
3.europe.pool.ntp.org has address 194.238.48.3
3.europe.pool.ntp.org has address 212.13.207.101

Try using this config:

server 0.europe.pool.ntp.org iburst
server 1.europe.pool.ntp.org iburst
server 2.europe.pool.ntp.org iburst
server 3.europe.pool.ntp.org iburst

-- 
Sphinx of black quartz judge my vow.



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