Bind dns server zone file

Linux and Unix-Like Ubuntu
1

I have a couple of zone conf files for the BIND server.
There are some records that contains the "IN" statement and some do not.
But anyway this works.
So my question is what this "IN" is intended for?
Here is the zone file example:

ORIGIN .
$ttl 60
example.com.    IN      SOA     ns1.example.com. hostmaster.example.com. (
                        2012030914
                        300
                        3600
                        600
                        86400 )
                        NS      ns1.example.com.
                        A       192.168.12.71
                        MX      10 webmail.example.com.
$ORIGIN example.com.
jira                    A       192.168.24.32
localhost               A       127.0.0.1
ns1                     A       192.168.12.15
qa                      A       192.168.12.22
webmail                 A       192.168.12.68
webmin.example.com.     IN      A       192.168.13.151
pmp.example.com.        IN      A       192.168.12.13
example.com.    IN      A       192.168.12.14
testsrvx.example.com.   IN      A       192.168.13.124
cisco.example.com.      IN      A       192.168.12.13
provisioning.example.com.       IN      A       192.168.13.151
zabbix.example.com.     IN      A       192.168.12.69
ca.example.com. IN      A       192.168.13.151
test1.example.com.      IN      A       127.0.0.1
2

Class = IN = Internet Protocol

List of DNS record types - Wikipedia, the free encyclopedia

http://tools.ietf.org/html/rfc1035

3.2.4. CLASS values

CLASS fields appear in resource records. The following CLASS mnemonics
and values are defined:

IN 1 the Internet

CS 2 the CSNET class (Obsolete - used only for examples in
some obsolete RFCs)

CH 3 the CHAOS class

HS 4 Hesiod [Dyer 87]

BTW, names ending in '.' are not tried with domain name prefixes. Often, the domain is also a host, like an email or web server. If an email server, it may have a stub web server to redirect everyone to www.domain.

1 Like
3

So this means that in my case the following record:

webmin.example.com.     IN      A       192.168.13.151

and the record:

webmin.example.com.      A       192.168.13.151

will mean the same and have the same response to a query?

4

I would guess most of us are doing IN ! It might be more necessary for dotted names in left. I suppose you could say it every time just to be safe and more consistent. Try it.

5

For BIND, the class field is optional. If the class field is omitted, the class IN is assumed.