Simple explanation for .zone file syntax required

[Stark]

Is there a link to somewhere that describes the different sort of naming syntax in a .zone file? I want to use the mail exchange aliases and shit, but everthing I've found either involves learning the history of BIND or waves its hand and says 'this includes the hostname-ip resolution'.

All I want to be able to do is build a .zone file containing a few simple hostname:ip pairs and a few of the other ones like MX. Why is it so hard to find out how?

[Spacebeard]

The best reference I've ever found is the official Bind 9 Reference Manual. This isn't bad either, though it's scattered around several different pages. Anyway, by way of quick explanation, here's one of mine, sanitized with hostnames and IP addresses changed:

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$TTL 86400;
dummy.org.    IN SOA  a.dummy.org. hostmaster.dummy.org. (
                        2005021614;
                        18000;
                        3600;
                        604800;
                        86400;
                        )
                        NS                      ns.dummy.org.
                        MX                      10 mx.dummy.org.
ns.dummy.org.           A       192.168.0.1
b.dummy.org.            A       192.168.0.2
c.dummy.org.            A       192.168.0.3
d.dummy.org.            A       192.168.0.4
a.dummy.org.            CNAME   ns.dummy.org.
e.dummy.org.            A       192.168.0.5
f.dummy.org.            A       192.168.0.6
mx.dummy.org.           A       192.168.0.7
www.dummy.org.          CNAME   mx.dummy.org.
g.dummy.org.            CNAME   mx.dummy.org.
h.dummy.org.            CNAME   mx2.dummy.org.
mx2.dummy.org.          A       192.168.0.8
i.dummy.org.            A       192.168.0.9
www2.dummy.org.         CNAME   j.dummy.org.
j.dummy.org.            A       192.168.0.10
k.dummy.org.            A       192.168.0.11

Section by section...

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dummy.org.    IN SOA  a.dummy.org. hostmaster.dummy.org. (

This line should begin with the domain, then the master name server ("source of authority"), then a contact email address (with a '.' instead of '@').

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                        2005021614;
                        18000;
                        3600;
                        604800;
                        86400;

The first number here is the serial number; it can be anything you want, but usual practice is to use a timestamp in YYYYMMDDHH format. It should be increased whenever the zone file is edited, so that BIND will reload the updated zone on startup.

The next four are the refresh time (how long slave servers will wait before querying the master about zone updates), the retry time (how long slave servers will wait before retrying a failed query to the master), the expiration time (how long a slave server's replica of the zone remains valid if it can't contact the master), and the negative TTL (how long negative answers to queries, ie a host not found, will be cached). These will rarely vary substantially between different zones.

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                        NS                      ns.dummy.org.
                        MX                      10 mx.dummy.org.

The nameservers and mail exchangers for the domain. You can have multiple NS records. You can also have mutlple MX records, each with a different priority; the lowesr priority will be preferred. Note that you can only define NS and MX records with names that are defined later on by A records; you can't use IP addresses or a CNAME.

Everything below is fairly straightforward... an address (A) record is defined by the full hostname (including trailing '.') followed by "A" and the address. A CNAME is an alias that points to an existing A record.

By the way, this is one reason why many people prefer to use alternative DNS servers like djbdns or maradns (another is security; BIND has a poor security record). I used djbdns briefly some time ago, but I don't remember it well enough to say anything about it.

[Pu-239]

Gah- don't remind me- I spent forever configuring one (so that I could refer to my computers by name w/o hosts files...).

[Stark]

Thats excellent, thanks guys. I tried to configure named when I built my server, gave up in disgust (the DNS-HOWTO is so fucking useless from a quick, simple setup) and now I have to know the line syntax for an exam. Later I'll post any specific questions I've got, but I think you've already made it alot clearer.

I love SDN.