localhost or LAN addresses in /etc/hosts

Derek Broughton news at pointerstop.ca
Fri Dec 12 18:51:26 UTC 2008

Chris G wrote:

> How does one decide whether to put a machine's name as a localhost
> address or an actual LAN address in /etc/hosts?
> My ubuntu server machine's name is isbd, this appears in three places
> in /etc/hosts at the moment:-
>   isbd    localhost.localdomain   localhost
> isbd
> home.isbd.net isbd 84-45-228-40.no-dns-yet.enta.net
>     chris.isbd.net
> This is all very well until one runs something like dnsmasq and get
> localhost addresses when asking for the address of isbd.
> I think the is redundant and should be removed,

I'd say you're just thoroughly misconfigured.  You _can't_ have isbd be 
all three addresses.  Personally, I don't think if you're running 
dnsmasq, isbd should be in there at all - _that's_ why you're running 
your own DNS.

> can I also
> remove the isbd from the line as well?  Why does it get put
> there, maybe it's there for use when the machine gets its IP via DHCP
> and thus it isn't fixed.

No.  It's got nothing to do with DHCP. and are, for 
all intents, the same address (the address of your "lo" interface - any address on the 127 subnet is masked to   The advantage of 
using different numbers is that something like Apache's virtual hosts can 
then see a different IP for each hostname - even though to the network, 
it's the same.

The, address _is_ likely DHCP related - at least, it was 
probably assigned by your router, and if so IT SHOULDN"T EVEN APPEAR in 
Now, the real question is what do you mean by "asking for the address of 
isbd"?  isbd is, by definition, your local machine, therefore a DNS 
lookup should always give you 127.x.x.x.  If you mean that you want the 
address of the host "isbd" on your local network, then the name is 
probably something like "isbd.isbd.net"

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