caching-namserver

[Bob Goodwin]

*jdow wrote:*
> *From: "Bob Goodwin" <bobgoodwin at wildblue.net>
> *
>> **Ed Greshko wrote:*
>> *
>>> **Bob Goodwin wrote:
>>> *
>>> *
>>>> **I've done "yum install caching-nameserver" and with a few crude 
>>>> tests
>>>> it appears that it might be working.
>>>>
>>>> Is there a file of cached addresses that I can look at and see that
>>>> they are actually being cached?
>>>> *
>>>> *
>>> **
>>> Not that I know of....
>>>
>>> However, you can do a "host -v somehost.com" were somehost is equal 
>>> to a
>>> host name you've not visited.  The first time you do it you may see
>>> something like:
>>>
>>> Received 194 bytes from 127.0.0.1#53 in 1291 ms
>>>
>>> But if you do it again, and it is working, you should see something on
>>> the order of:
>>>
>>> Received 194 bytes from 127.0.0.1#53 in 1 ms
>>> *
>>> * 
>> **Ok, I tried:
>> *
>>
>> *host -v speakeasy.net *
>>
>> *First time:
>>
>> Received 109 bytes from 127.0.0.1#53 in 745 ms
>>
>> Second time:
>>
>> Received 109 bytes from 127.0.0.1#53 in 105 ms
>>
>> That would seem to indicate that it works?
>>
>> I'm not sure it's of much value considering the round trip time to 
>> the satellite but I guess every little bit helps.  I was timing the 
>> "Looking up google.com" or whatever at the bottom of the Thunderbird 
>> screen and timing that.  It looked faster after the initial trial ...
>> * 
> *
> No - that would include cached images and all that nonsense. Use the
> commandline and something like "host nlzero.com", one I bet you have
> never touched before. Google you have touched before regularly and
> is probably still cached.
>
> Round trip to the satellite? Then the second one did not come via
> the satellite. But the delay is incredibly long for coming from
> something local. (The first one does look like a satellite hop round
> trip, potentially. One hop is a touch over 1/4 second absolute minimum.
> Add to that some overhead for communications reliability and the
> satellite's processing time, also.)
>
> {^_^}
>
> * 
*Yeah, the satellite introduces a bit less than 500 ms of delay for transit
time in addition to the usual system delays.  When I look at ntpq I see
typically 600-700 ms there.

I thought the 100 ms I'm seeing for the local dns looked long but I have no
experience other than this.  As it is it's till less than the 700-800 
otherwise. 
Yes, I understand that google is frequently used and should be in the 
local cache,
that was merely an example, thought I made that clear.

Bob Goodwin
*