[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: what is the static ip address I assigned to eth0?



Quoting Reco (recoverym4n@gmail.com):
> On Fri, 28 Aug 2015 14:35:09 +0100
> Brian <ad44@cityscape.co.uk> wrote:
> > On Fri 28 Aug 2015 at 14:45:32 +0300, Reco wrote:
> > > On Fri, 28 Aug 2015 12:09:08 +0100
> > > Brian <ad44@cityscape.co.uk> wrote:
> > > > On Fri 28 Aug 2015 at 10:01:59 +0000, Curt wrote:
> > > > > On 2015-08-28, David Wright <deblis@lionunicorn.co.uk> wrote:
> > > > > >
> > > > > > $ host localhost
> > > > > > Host localhost not found: 3(NXDOMAIN)
> > > > > > $ ping localhost
> > > > > > PING localhost (127.0.0.1) 56(84) bytes of data.
> > > > > > 64 bytes from localhost (127.0.0.1): icmp_req=1 ttl=64 time=0.032 ms
> > > > > 
> > > > > curty@einstein:~$ host localhost
> > > > > localhost has address 127.0.0.1
> > > > > localhost has IPv6 address ::1
> > > > 
> > > > To complete the picture:
> > > > 
> > > >   brian@desktop:~$ dig -x 127.0.0.1
> > > > 
> > > >   ; <<>> DiG 9.9.5-9-Debian <<>> -x 127.0.0.1
[...]
> > > >   ;; ANSWER SECTION:
> > > >   1.0.0.127.in-addr.arpa. 10800   IN      PTR     localhost.
[...]
> > > > host and dig use only the DNS.
> > > > 
> > > > Elimar's suggestion to use 'host $(hostname)' will work if hostname is
> > > > a FQDN. But it shouldn't (or wouldn't) be on a stock Debian system.
> > > 
> > > Not unless said 'stock Debian system' has 'search <domain>' stanza
> > > in /etc/resolv.conf.
> > 
> > Does "search example.org" count? :)
> 
> It should count for the hosts in this domain. Provided, of course, that
> one needs to resolve 'bare' hostnames (i.e. non-FQDN).
> 
> > What is not understandable (to me) is why 'host localhost' resolves for
> > some but not for others and why it is thought 'host $(hostname)' should
> > resolve in the DNS.
> 
> Stock Debian BIND configuration includes this wonderful snippet
> (/etc/bind/db.local):
> 
> ;
> ; BIND data file for local loopback interface
> ;
> $TTL    604800
> @       IN      SOA     localhost. root.localhost. (
>                               2         ; Serial
>                          604800         ; Refresh
>                           86400         ; Retry
>                         2419200         ; Expire
>                          604800 )       ; Negative Cache TTL
> ;
> @       IN      NS      localhost.
> @       IN      A       127.0.0.1
> @       IN      AAAA    ::1
> 
> Translating this to English - every BIND installed on Debian considers
> itself the final authority on "localhost" zone and always returns
> 127.0.0.1 for A queries (IPv4) and ::1 for AAAA queries (IPv6).
> Other Linux distributions can store zone files elsewhere, but the
> principle is the same.
> Interpreting /etc/bind/db.127 (PTR entries) is left for an exercise for
> the readers.
> 
> So - 'host localhost' *should* work given an ideal world (because in
> ideal world everyone will use an ideal DNS, which is BIND).

Why on earth would I want to use BIND on my LAN at home? Just so I
have to read and understand RFC1035? No, I just put the hostnames
and addresses into /etc/hosts. (And script it because I have five
to do.)

Debian correctly puts   127.0.0.1 localhost   into /etc/hosts and
hosts: files mdns4_minimal [NOTFOUND=return] dns
into /etc/nsswitch.conf. So it's the hosts file that resolves
localhost. DNS is not involved. BIND has to know the answer *in case*
it's asked, not because it's *got to be* asked.

My earlier posting (included above) was to show that, of the many
suggestions made in this thread, "host" was not a good choice on a
typical correctly-configured system.

Cheers,
David.


Reply to: