[PLUG] Spotty DNS Resolution

Daniel Hedlund daniel at digitree.org
Sat Oct 14 23:50:14 UTC 2006


Aaron Ten Clay wrote:
> This is likely your problem. Most DNS servers these days, it seems, give up 
> after about 2000ms if they can't get the info you want. Especially when just 
> doing forwards. The DNS scheme is that you have multiple servers so if one is 
> down/unreachable you can keep trying all the servers for a zone. Since most 
> software doesn't seem to do that anymore, your listing a non-DNS server as a 
> server for your domain is likely the cause of the problem. Resolvers are 
> probably trying that one first, and giving up.

Timeouts could be a very likely issue and may be my main problem.  There 
is always a possibility on the server that the DNS response might lag by 
a couple of seconds.  This is because I don't have very much memory on 
the machine and some other services on the box might cause BIND to swap 
out of memory at the wrong time.  Good suggestion; not much I can do 
about it besides get more memory or move it to another box (ie. OpenWRT 
router or something).


> In cases where I've had no other options, I've run a second IP on one host and 
> listed both IPs as the two nameservers for a domain. No redundancy, but at 
> least all DNS requests are satisfied if the host is up (and any services on 
> that host would be down if the host were down, anyway, negating any benefit 
> to redundancy)

This is what I used to do several years ago.  Getting a second IP 
address in the short term is a no go as I'm getting ready to move in a 
couple of days (servers will stay "for now"), but may be viable in a 
month or so.  When I moved overseas I was able to update Dotster's DNS 
server list to only have a single entry so I only had one IP address 
there which worked well.  When I moved back to Portland and set up a 
server here, Dotster had updated their inteface to require a minimum of 
two servers (very annoying).


> If all else fails, you could use everydns.net for a secondary server. I've 
> used them for a while now without any problems. (Free/donation requested 
> service)

I tried a similar service to everydns.net once a couple years ago; I 
can't remember the name of it but I don't think it was everydns.  I 
wound up losing my DNS records for almost a week it suddenly stopped 
serving my domain.  I will consider trying everydns, thanks.

Cheers,

Daniel Hedlund
daniel at digitree.org



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