/etc/hosts - how does that file work?? - was weird nfs issues.

Peter fbsdq at peterk.org
Thu Jun 4 20:27:20 UTC 2009

> On Thursday 04 June 2009 20:48:21 Peter wrote:
>> iH,
>>   This all started with NFS not mounting at boot....so, testing in VMs:
> <snip>
>> Why is ping using one IP, and ssh/mount_nfs/showmount using another IP
from /etc/hosts?
> Q: Where is described that name resolution for A or PTR records should
> returned in a fixed order and that a consumer should always use the
> one
> returned?
> A: Nowhere. Name servers are encouraged to do round-robin returns if not
specified otherwise. Applications may sort/pick at their own leisure.
> --
> Mel

I do not think /etc/hosts does round robin, I always assumed first match
wins...DNS/bind I would understand...

Why does ping always return the address,
 and ftp,nc,ssh,telnet,fetch _always_ uses the 116 address?

I would assume at least sometimes it would hit the 172 address with
anything besides ping - but it only ping hits the 172 address...
If so, I'd guess there would be consistency between ping lookups and
'telnet/ssh/etc' lookups...

Why if the last octet is bumped up, everything _always_
returns the 172 address?

client# grep server /etc/hosts              server.test server             server.test server
client# telnet server
telnet: connect to address Connection refused

/etc/hosts - 'server' changed to

client# telnet server
telnet: connect to address Operation timed out
telnet: connect to address Connection refused
telnet: Unable to connect to remote host

if server has ip>, it always uses the 172 address first...

but ping always uses the  172...
even if third entry is added into /etc/hosts - nothing ever uses it as the
first/primary IP.

Is there an algorithm based on IP/program being used and the returned IP?

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