Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual page 312

Line 6:
The expiration time specifies the time frame after which a secondary name
server discards the cached data if it has not regained contact to the primary server.
Here, a week.
Line 7:
The last entry in the SOA record specifies the negative caching TTL—the
time for which results of unresolved DNS queries from other servers may be cached.
Line 9:
The IN NS specifies the name server responsible for this domain. dns is extended
to dns.example.com because it does not end with a ".". There can be several
lines like this—one for the primary and one for each secondary name server. If
notify is not set to no in /etc/named.conf, all the name servers listed here
are informed of the changes made to the zone data.
Line 10:
The MX record specifies the mail server that accepts, processes, and forwards e-
mails for the domain example.com. In this example, this is the host
mail.example.com. The number in front of the hostname is the preference
value. If there are multiple MX entries, the mail server with the smallest value is
taken first and, if mail delivery to this server fails, an attempt is made with the next
higher value.
Lines 12–19:
These are the actual address records where one or more IP addresses are assigned
to hostnames. The names are listed here without a "." because they do not include
their domain, so example.com is added to all of them. Two IP addresses are as-
signed to the host gate, as it has two network cards. Wherever the host address
is a traditional one (IPv4), the record is marked with A. If the address is an IPv6
address, the entry is marked with AAAA.
NOTE: IPv6 Syntax
The IPv6 record has a slightly different syntax than IPv4. Because of the
fragmentation possibility, it is necessary to provide information about
missed bits before the address. To just fill up the IPv6 address with the
needed number of "0", add two colons at the correct place in the address.
298 Administration Guide