15 Setting Up a DNS Server

This chapter provides instructions on setting up a DNS server in UNIX. These instructions are applicable for setting up the site-specific DNS zones used for hostname resolution in the example in Figure 11-7, "DNS Resolution Topology Overview".

Note:

The DNS setup information provided in this chapter is an example to aid in the understanding of OracleAS Disaster Recovery operations. It is generic to DNS, and other appropriate DNS documentation should be consulted for comprehensive DNS information.

For the discussion in this chapter, the DNS server that is set up creates and services a new DNS zone with the unique domain oracleas. Within the zone, this DNS server resolves all requests for the oracleas domain and forwards other requests to the overall wide area company DNS server(s).

On the UNIX host that will act as the DNS zone server, perform the following steps:

Create the name server configuration file /var/named.conf. Assuming the wide area company DNS server IP address is 123.1.15.245, the contents of this file should be as follows:

options {
          directory "/var/named";
          forwarders {
           123.1.15.245;
         };
};

zone "." in {
              type hint;
              file "named.ca";
};

zone "oracleas" {
                  type master;
                  file "oracleas.zone";
};

zone "0.0.127.IN-ADDR.ARPA {
                           type master;
                           file "127.zone";
};

Create the root hint file /var/named/named.ca, which has the following contents (123.1.2.117 is the IP of the zone DNS server):
```
.        999999   IN    NS    ourroot.private.
ourroot.private.   IN    A     123.1.2.117
```

Create the loopback address file /var/named/127.zone, which has the following contents (assume the zone DNS server's hostname is aszone1):

$ORIGIN    0.0.127.IN-ADDR.ARPA.
0.0.127.IN-ADDR.ARPA.    IN    SOA  aszone1.oracleas.  root.aszone1.oracleas.
(
           25           ; serial number
           900          ; refresh
           600          ; retry
           86400        ; expire
           3600       ) ; minimum TTL

0.0.127.IN-ADDR.ARPA.    IN    NS    aszone1.oracleas.
1                        IN    PTR   localhost.oracleas.

Create the zone data file /var/named/oracleas.dns, which has the following contents (values shown are applicable to the example of the production site in Figure 11-7):

;
;  Database file oracleas.dns for oracleas zone.
;    Zone version:  25
;
$ORIGIN oracleas.
oracleas.       IN    SOA    aszone1.oracleas.  root.aszone1.oracleas (
                25        ; serial number
                900       ; refresh
                600       ; retry
                86400     ; expire
                3600    ) ; minimum TTL

;
;    Zone NS records
;
oracleas.       IN        NS    aszone1.oracleas.

;
;    Zone records
;
localhost       IN     A     127.0.0.1

asmid1          IN     A     123.1.2.333
asmid2          IN     A     123.1.2.334
infra           IN     A     123.1.2.111
remoteinfra     IN     A     213.2.2.210

Run the following command to start the name server:
```
/sbin/in.named
```
On all the hosts in the domain that is serviced by this DNS server, edit the domain and nameserver settings in the file /etc/resolv.conf as follows (all previous nameserver settings should be removed; 123.1.2.117 is assumed to the zone DNS server's IP address):
```
domain    oracleas
nameserver 123.1.2.117
```