DNS problems this morning -

[Rick Stevens]

On 11/13/2012 11:12 AM, Bob Goodwin - Zuni, Virginia, USA issued this 
missive:
> On 13/11/12 13:06, Rick Stevens wrote:
>> You don't. You put the entries in the /etc/resolv.conf file and the
>> resolver library picks them up.
>>
>>> The 5 second
>>>     timeout seems much to long when combined with 5 tries, perhaps fewer
>>>     tries would be better? However I imagine there were good reasons for
>>>     the defaulsts ...
>>
>> If you've ever run a big network (or a really popular one) you can watch
>> the DNS servers get pummeled--especially if you have short TTLs set on
>> the records. That being said, even a busy name server should respond in
>> 5 seconds or less, so that seems reasonable.
>>
>> The default retry count is 2 (not 5) so the defaults as stated would
>> result in a 10 second delay before the second DNS server is consulted.
>> Yes, that seems an eternity, but not everyone has fast Internet access.
>> There are still people with dial-up service (hard to believe, but
>> they're out there). The standards were set up to accommodate these
>> older environments. If you want a true giggle, look up RFC 1149,
>> "Transmission of IP Datagrams on Avian Carriers" and be glad that it
>> never caught on. :-)
>>
>> You can put in as long a timeout or as many retries as you want, but
>> the library will limit timeouts to no more than 30 seconds (even if you
>> specify 45) and no more than 5 retries (even if you specify 10). That's
>> what the "silently capped" bit means.
>
>     I've tried the following:
>
>         # Generated by NetworkManager
>         nameserver 127.0.0.1
>         nameserver 192.168.1.1
>         nameserver 184.63.128.68
>         timeout:1
>         attempts:1
>
>     I moved 127.0.0.1 to the first line and added the last
>     two limitations.
>
>     The only way I have to judge time is watching the bottom of the
>     Firefox display where it tells me it's "Looking up" an address and
>     doing a number of reloads on a complex page,  e.g.
>     http://www.weather.com/weather/tenday/23898. It appears to moving
>     through rapidly, I don't see it dwelling on "Looking up" but for a
>     fraction of a second, spending more time transferring data.
>
>     Is there a better way to test?

Format is "options timeout:1 attempts:1", and I'd move it above the
"nameserver" lines.
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- Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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- Grabel's Law: 2 is not equal to 3--not even for large values of 2. -
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