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Maintaining DNS

info

This guide assumes you've already gone through setting up BIND tutorial.

Add record in forward lookup zone file:​

Increment serial​

caution

Always increase the serial number, it can never decrease.

Serial numbers within the zone files must always be increased after editing.Technically speaking this is done in a master-slave scenario with multiple dns servers. When the change occurs in the master, the slave dns servers will see the serial number has increased and update as well.

/var/named/zones/internal.virtnet
$TTL    604800
@       IN      SOA     dns-dhcp.internal.virtnet. admin.internal.virtnet. (
            2020091010  ; Serial //old value of serial was 2020091000
//rest of config clipped for brevity

Add A record:​

/var/named/zones/internal.virtnet
//beginning of config clipped for brevity
; 172.16.0.0/16 - A records
foreman.internal.virtnet.       IN      A       172.16.0.10
ldap1.internal.virtnet          IN      A       172.16.0.11 //new entry
ldap2.internal.virtnet          IN      A       172.16.0.12 //new entry

Add record in reverse lookup zone file:​

Increment serial​

/var/named/zones/16.172.rev
$TTL    604800
@       IN      SOA     internal.virtnet. admin.internal.virtnet. (
            2020091010  ; Serial //old value of serial was 2020091000
//rest of config clipped for brevity
/var/named/zones/16.172.rev
//beginning of config clipped for brevity
; PTR Records
0.8       IN      PTR     dns-dhcp.internal.virtnet.      ; 172.16.0.8
0.10      IN      PTR     foreman.internal.virtnet.       ; 172.16.0.10
0.11      IN      PTR     ldap1.internal.virtnet.         ; 172.16.0.11
0.12      IN      PTR     ldap2.internal.virtnet.         ; 172.16.0.12

Reload named​

It is possible to restart named, however if the server is both authoritative for the zone and recursive for users then restarting named will discards cached entries from other domains. As such, it is advisable to use rdnc reload to keep the cached entries and update changes.

sudo rndc reload