3.14. DNS server configuration
As a starting point we use the default caching only nameserver configuration provided by SuSE. The caching only name server forwards requests to other nameservers provided by keyword forwarders and caches the answers for better performance. This configuration is good enough if you only need to resolve names and addresses in the Internet.
In order to use local name resolution too, we add two new zone records: residency.local (name to IP address), and 100.168.192.rev for reverse name resolution (IP address to name). For debugging, we add the logging section because it forces the name server daemon to log all requests in /var/log/messages.[18]
[18] For more information see BIND 9 Administrator Reference Manual: http://www.bind9.net/Bv9ARM.html
Example 3-27. /etc/named.conf
options {
directory "/var/named";
forwarders {
9.12.6.7;
};
listen-on { any;};
notify no;
forward first;
};
zone "localhost" in {
type master;
file "localhost.zone";
};
zone "0.0.127.in-addr.arpa" in {
type master;
file "127.0.0.zone";
};
zone "." in {
type hint;
file "root.hint";
};
# You can insert further zone records for your own domains below.
logging {
category queries {
default_syslog;
};
category update {
default_syslog;
};
};
zone "residency.local" {
type master;
file "/var/named/residency.local.hosts";
};
zone "100.168.192.in-addr.arpa" {
type master;
file "/var/named/100.168.192.rev";
};
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Now we create our own local zone files: residency.local, and for reverse lookup, 100.168.192.rev. We need a residency.local file in order to be able to resolve names to IP addresses.
Example 3-28. /var/named/residency.local
$ttl 38400 residency.local. IN SOA 192.168.100.110. root.p630sles. (
0310221736 ; serial
10800 ; refresh
3600 ; retry
604800 ; expiry
38400 ) ; minimum
residency.local. IN NS 192.168.100.81
$GENERATE 111-254 node-$ A 192.168.100.$
lpar8.residency.local. IN A 192.168.100.84
lpar7.residency.local. IN A 192.168.100.83
lpar6.residency.local. IN A 192.168.100.82
lpar5.residency.local. IN A 192.168.100.81
lpar4.residency.local. IN A 192.168.100.80
lpar3.residency.local. IN A 192.168.100.79
lpar2.residency.local. IN A 192.168.100.78
lpar1.residency.local. IN A 192.168.100.77
p630sles.residency.local. IN A 192.168.100.110
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Important
Every time you change something in the zone file, you need to change the serial number in the second line.
In order to resolve addresses to names, we need a file for reverse name resolution. In this file, addresses are written in opposite order: 77.100.168.192, instead of 192.168.100.77.
Example 3-29. /var/named/100.168.192.rev
$ttl 38400100.168.192.in-addr.arpa. IN SOA p630sles. root.p630sles. (
9998899999
10800
3600
604800
38400 )
100.168.192.in-addr.arpa. IN NS p630sles
77.100.168.192.in-addr.arpa. IN PTR lpar1.
78.100.168.192.in-addr.arpa. IN PTR lpar2.
79.100.168.192.in-addr.arpa. IN PTR lpar3.
80.100.168.192.in-addr.arpa. IN PTR lpar4.
81.100.168.192.in-addr.arpa. IN PTR lpar5.
82.100.168.192.in-addr.arpa. IN PTR lpar6.
83.100.168.192.in-addr.arpa. IN PTR lpar7.
84.100.168.192.in-addr.arpa. IN PTR lpar8.
110.100.168.192.in-addr.arpa. IN PTR p630sles.
$GENERATE 111-254 $ PTR node-$.
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Tip
The trick in both zone files is in the line starting with $GENERATE: it will assign all nodes above 111 names; that is, node-111, node-112 and so on. This is a useful feature in combination with a dhcpd server for a larger environment or cluster, because you do not need to add nodes one by one anymore.