Re: netstat performance
On Jun 29, 2011, at 11:51 AM, William Hopkins wrote:
> On 06/29/11 at 10:15am, ChadDavis wrote:
>> Not a big deal, but just made me think. Surely the name resolution
>> isn't that costly is it?
>
> Depends on latency and distance to your DNS server, how long it takes the DNS
> server to perform the recursive query or forward to a server which does,
> whether you have the answer cached locally or at any of the servers along the
> way, etc. So it can vary wildly.
Exactly. If you keep a well populated /etc/hosts, it'll be snappy as hail -- it's a disk hit (if your resolver is configured to go to hosts first, and you keep hosts updated). If your computer has to go to your ISP for cached info, that's a 'Net hit, and can take some time, depending on your latency and bandwidth. If your ISP doesn't have the lookup cached, there are several 'Net hits involved.
If you have a cacheing DNS server locally, you can save significant time on DNS lookups -- cached stuff is (best case) a RAM hit, worst case, Ethernet.
For a good time, 'apt-get install bind' :-)
--
Glenn English
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