[ale] /etc/hosts and caching

[Lightner, Jeff]

Hard coding IPs into applications is generally a bad idea because later you might not remember everything you have to change if your IPs change.

As others have said test things out but if /etc/hosts is actually causing you serious delays I'd suggests your box has other issues going on (e.g. heavily loaded root disk, insufficient CPU or memory) and addressing those underlying issues is going to give you more overall performance in the long run than focusing on host name resolution because those underlying issues likely affect other things as well.





-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Damon L. Chesser
Sent: Sunday, November 06, 2011 12:31 PM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] /etc/hosts and caching

On Sat, 2011-11-05 at 13:28 -0400, Richard Bronosky wrote:
> Geeh, I'm glad someone read my demo! You can talk all day long, or you
> can code a proof. I encourage my developers to do that because at
> least 20% of what they find on the internet doesn't apply because of
> config differences.
>
> I also would encourage the OP to try putting IP addresses into the
> applications to see what that does for performance. Unfortunately the
> concept of "test instead of talk" does not go very far on this list.

Actually, I appreciate the test.  We were also talking about just using
IPs in the application vs hostnames.  however, I don't yet have access
to those boxes, so I was gathering information. Change control and all
that.
>
> On Nov 5, 2011 10:10 AM, "leam hall" <leamhall at gmail.com> wrote:
>         yeah, it took me a sec to figure out why you did that, but it
>         makes sense. Your example shows that for that
>         purpose /etc/hosts file changes are updated immediately. With
>         "immediate" being defined as sub 1 second.
>
>         I would assume there are edge cases where nscd causes issues.
>         Not sure what they are but with the wide spread usage of Linux
>         there are probably some places.
>
>         Leam
>
>
>         On Fri, Nov 4, 2011 at 6:42 PM, Richard Bronosky
>         <Richard at bronosky.com> wrote:
>                 What is important to note about that example is that
>                 ping, like most applications that do network lookups,
>                 will only do the lookup once at the beginning. For
>                 that reason my example required that I put single ping
>                 calls in a loop
>
>
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--
Damon
damon at damtek.com

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