DNS files .

gardenair · 07-05-2010, 12:22 AM

hi,
To configure DNS server in Linux normally we use BIND software. I am new in Linux and there are some few files which play role in configuring Linux DNS server.

1- /etc/hosts

2- /etc/resolv.conf

3- /etc/nsswitch.conf

4- /etc/named.conf

Please just in brif can you guide me about each file i.e when we should use /etc/hosts,resolve.conf ,nsswitch.cong ,and named.conf and what are there limitations?

thanks in advance
mypass

subho.d · 07-05-2010, 04:49 AM

hi ;
for server u need fwd zone file & bak zone file ...

routers · 07-06-2010, 10:58 AM

Quote:

Originally Posted by gardenair

hi,
To configure DNS server in Linux normally we use BIND software. I am new in Linux and there are some few files which play role in configuring Linux DNS server.

1- /etc/hosts
-------------------------------------
anything written inside this file will override the system query
as example see below
[noc@nc ~]$ ping ads.doubleclicks.net
PING ads.doubleclicks.net (127.0.0.1) 56(84) bytes of data.
64 bytes from nc (127.0.0.1): icmp_seq=1 ttl=64 time=0.070 ms
64 bytes from nc (127.0.0.1): icmp_seq=2 ttl=64 time=0.054 ms

this is because i added in this file as following
[noc@nc ~]$ cat /etc/hosts |grep ads
127.0.0.1 ads.doubleclicks.net

-----------------------------------

2- /etc/resolv.conf
------------------------------------
this file is the place you put to point your dns system query
to any named server
--------------------------------------

3- /etc/nsswitch.conf
----------------------------------
simple i dont know and never touch
------------------------------

4- /etc/named.conf
---------------------------------------
this file is for bind configuration to call zone file path
normaly this is symlink from /var/named/chroot/etc/named.conf

if your bind chrooted and if you want to see the file symlink or not

just use ls -l /etc/named.conf

-------------------------------------

Please just in brif can you guide me about each file i.e when we should use /etc/hosts,resolve.conf ,nsswitch.cong ,and named.conf and what are there limitations?

thanks in advance
mypass

I not sure about the limitation in which area

chrism01 · 07-06-2010, 07:49 PM

1. /etc/hosts
usually just the loopback address(es) ie

127.0.0.1 localhost.localdomain localhost

and sometimes ip/name of the system if static eg

192.168.0.1 mysystem.mydomain mysystem

2. /etc/resolv.conf
when your system needs to find another machine, look in here for the DNS servers to ask (usually those of your ISP).

2. /etc/nsswitch.conf

various stuff; basically specifies eg

networks: files dns

means when looking for another system, check local files first ie /etc/hosts. If not found, ask DNS ie resolv.conf

4. named.conf

config file for a DNS (aka BIND) server

See http://www.linuxtopia.org/online_boo...ion/index.html for some good explanations/howto

grail · 07-06-2010, 08:44 PM

@Chris - Just to confirm, as it is a rhel site, the information is fairly universal?
Just curious as i will be looking at this shortly but will be using a do it yourself (LFS variant) version.

salasi · 07-07-2010, 03:46 AM

Maybe, the subject of this (samba and windows) doesn't sound promising, but the early coverage of how Unix name resolution works is good.

for something like Bind itself there are tutorials and books aplenty, but try
Bind
Bind
and the Ablitz/Liu book.

Quote:

To configure DNS server in Linux normally we use BIND software.

We?? Well, it probably should not be an option that we accept without thinking. For simpler cases, BIND unnecessarily complicates set-up, and its history hardly makes you feel that it is a 'set and forget' solution if you want security. There are certainly some cases where BIND is a valid option, but taking it as the default option which is always accepted is probably not the right thinking.

chrism01 · 07-07-2010, 11:17 PM

@grail: the fundamentals don't usually vary between distros. The above is a good start, but read that link of mine. The one that can vary is the location (but not the content) of the BIND files ie named.conf and associated files.
For security, RH and some others put it under a chrooted dir (see link for details: chap 16).

Quote:

If you have installed the bind-chroot package, the BIND service will run in the /var/named/chroot environment. All configuration files will be moved there. As such, named.conf will be located in /var/named/chroot/etc/named.conf, and so on.