[CentOS] Is avahi essential?

Les Mikesell lesmikesell at gmail.com
Sat Jan 14 16:56:52 UTC 2012

On Sat, Jan 14, 2012 at 8:17 AM, Timothy Murphy <gayleard at eircom.net> wrote:
>>> Isn't that more or less what I said above?
>> It's almost the opposite.  mDNS does name->IP and let's people
>> find other machines; DHCP does MAC->IP and let's a machine find _itself_.
>> Or, another way of looking at it.  mDNS is a bit like ARP, but for names.

Somebody already said this but it isn't just host names, it is for
services and the ports they run on.

> OK, I should have said "a rival to ARP + dhcp".
> As I see it, dhcpd assigns IP addresses to the devices on a LAN,
> and arp then provides a method of accessing a device
> with a given IP address.
> Incidentally, I don't really see why mDNS is needed on a LAN.
> If a program wants to know the IP address of a device with a given name,
> why can't it just look in /etc/hosts ?

Devices aren't really the point.  Start a second copy of mediatomb
somewhere.  Change the port it runs on.  Start 2 copies on the same
server on different ports.  Tell the ps3 to find them.  Where is the
ps3's /etc/host file?  How would you edit it - and if you could, how
would you describe 2 of the same service on the same device?  If I
turn on a sony laptop running windows7, the ps3 sees both the windows
media server and the sony vaio instance of the similar service.

> I see that it might be useful in a much simpler setup,
> where there is no server;
> but if there is a server available, I don't really see the point of it.

A visitor with a laptop uses your wifi and would like to print
something.  With apple's bonjour (which can be installed on windows
too, and avahi probably matches) he'll see a list of available
printers without having to configure anything.  Isn't that nicer than
having to match IP/name/protocol/port up yourself all with different
configuration concepts?

   Les Mikesell
     lesmikesell at gmail.com

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