[MLB-WIRELESS] Melbwireless Digest, Vol 35, Issue 11

[Steven Haigh]

> -----Original Message-----
> From: melbwireless-bounces at wireless.org.au [mailto:melbwireless-
> bounces at wireless.org.au] On Behalf Of Tyson Clugg
> Sent: Wednesday, 20 August 2008 12:44 PM
> To: Adam Grigolato
> Cc: melbwireless at wireless.org.au
> Subject: Re: [MLB-WIRELESS] Melbwireless Digest, Vol 35, Issue 11
> 
> On Wed, 2008-08-20 at 12:09 +1000, Adam Grigolato wrote:
> > Im an experianced DNS admin,
> 
> So am I, so there.  :P

Gee, then what does that make me? ;)

> > it would be pretty easy to setup a DNS server like that,
> 
> Sure would be.  The zone file could be generated the same as a hosts
> file.

Perl + input data = any output you like.

> > the problem with the host file setup is that its not a fluid setup.
> > it has to be manually changed whenever there is a network change.
> 
> The manual update problem can be solved by using cron to periodically
> pull a new hosts file.

Mmmmm Hackingly good ;)

> > DNS and DHCP over that would be good in that regard to allow for a
> > dynamic setup,
> > well thats my 32.45 cents :D
> 
> The problem with a central DNS server is that our network isn't well
> enough connected to ensure lookups work from any part of the network.
> Setting up DNS service master/slave replication on OpenWRT is a bit of
> overkill and won't work if no link is available to wherever the master
> DNS server is located on the network.  A hosts file can be copied
> manually if necessary (yes, so can a zone file but you have to reload
> your DNS once done - another step that can go wrong).

Plus if you use BIND on OpenWRT, kiss goodbye to most of your disk space.
Sadly, whoever built BIND for OpenWRT did static linking on ALL binaries -
meaning huge executable filesize. Considering we're usually working with 8Mb
max (without USB keys etc etc), then this is a squeeze.

> In the early stages of the Internet before DNS came to be, there was
> indeed a global hosts file.  A hosts file works well when all the
> information can be gathered from a single source, such as our node
> database.  As soon as you wish to delegate responsibility to multiple
> sources, then DNS becomes useful.  At the moment I see no need to
> delegate DNS zones to poorly connected nodes throughout the network,
> especially since our node database already has all the information
> required to generate a decent hosts file.

DNS is just as complex. Lets see, a DNS zone for aaa.mw, another for aac.mw
etc etc - that's going to add up to a lot of zones very quickly. Syncing
those across multiple devices will be a pain.

> Also remember that a lot of our nodes are running on less than 8MB of
> RAM with limited CPU cycles available, and not everyone is a DNS admin.
> Think *simple* and everything is more likely to work the way we expect.

Oh yeah - OpenWRT is great, but everything has to be considered as low
footprint.

--
Steven Haigh

Email: netwiz at crc.id.au
Web: http://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897