Specifications

A
DNS — Domain Name Service
masters { 10.0.0.1; }; This entry is only needed for slave zones. It specifies
from which name server the zone file should be transferred.
allow-update { ! *; }; This options controls external write access, which
would allow clients to make a DNS entry — something which is nor-
mally not desirable for security reasons. Without this entry, zone up-
dates are not allowed at all. Note that with the above sample entry, the
same would be achieved because ! * effectively bars any clients from
such access.
Structure of Zone Files
Two types of zone files are needed: one serves to assign IP addresses to host
names and the other does the reverse — supplies a host name for an IP ad-
dress.
‘.’ has an important meaning in the zone files here. If host names are
given without ending with a ‘.’, the zone will be appended. Thus, complete
host names specified with a complete domain must end with a ‘.’ so the
domain is not added to it again. A missing point or one in the wrong place
is probably the most frequent cause of name server configuration errors.
The first case to consider is the zone file world.zone, responsible for the
domain world.cosmos, as in File 13.
1. $TTL 2D
2. world.cosmos. IN SOA gateway root.world.cosmos. (
3. 2001040901 ; serial
4. 1D ; refresh
5. 2H ; retry
6. 1W ; expiry
7. 2D ) ; minimum
8.
9. IN NS gateway
10. IN MX 10 sun
11.
12. gateway IN A 192.168.0.1
13. IN A 192.168.1.1
14. sun IN A 192.168.0.2
15. moon IN A 192.168.0.3
16. earth IN A 192.168.1.2
17. mars IN A 192.168.1.3
File 13: The File /var/lib/named/world.zone
163SuSE Linux – Firewall on CD2