network admin, ip addresses for webserver

[Karl Auer]

On Wed, 2014-10-29 at 20:55 +0000, Colin Law wrote:
> On 29 October 2014 04:10, Thufir <hawat.thufir at gmail.com> wrote:
> > To ballpark, what are the performance differences between allowing the PC
> > to use DHCP and have router assign a preferred ip address, versus an
> > actual static ip address?
> 
> I believe there will be effectively no difference.  The one running on
> DHCP will very occasionally ask for lease renewal but that is all.

No difference as long as things are working. If they stop working then
lots of things may happen:

- your PCs may lose their IP addresses
- they may be unable to get new ones
- they may get incorrect (unroutable) addresses
- they may get unusable ancillary info like bad gateways etc

That said, the benefits of dynamic addressing are pretty good:
- no need to configure systems manually
- you can update addresses, subnet masks, gateways, nameservers and
other info from one central point
- the DHCP server can log comings and goings
- systems can be moved from network to network without reconfiguration

And if you really need a PC to have one particular address, you can
reserve it in the DHCP server without having to manually configure the
PC.

So in general, you should strive to have all your systems using DHCP,
not statically configured addresses. Just be aware of the failure modes
so you can recognise and deal with them if they arise. Also think
carefully about lease times. For a production network, keep them between
6 and 24 hours unless you have very good reasons not to (a public or
wifi subnet might have much shorter lease times, like five minutes). For
a home network, it doesn't much matter, you can reboot stuff :-) The
lease time determines how quickly an address can be re-used. Long lease
times are more stable, but shorter lease times are more flexible and
responsive to change.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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