Chapter 24. The Domain Name System

Table of Contents

24.1. Configuration with YaST
24.2. Starting the Name Server BIND
24.3. The Configuration File /etc/named.conf
24.4. Zone Files
24.5. Dynamic Update of Zone Data
24.6. Secure Transactions
24.7. DNS Security
24.8. For More Information


DNS (domain name system) is needed to resolve the domain names and hostnames into IP addresses. In this way, the IP address is assigned to the hostname earth, for example. Before setting up your own name server, read the general information about DNS in Section 22.3, “Name Resolution”. The following configuration examples refer to BIND.

24.1. Configuration with YaST

You can use the DNS module of YaST to configure a DNS server for your local network. When starting the module for the first time, a wizard starts, prompting you to make just a few basic decisions concerning the server administration. Completing this initial setup produces a very basic server configuration that should be functioning in its essential aspects. The expert mode can be used to deal with the more advanced configuration tasks.

24.1.1. Wizard Configuration

The wizard consists of three steps or dialogs. At the appropriate places in the dialogs, you are given the opportunity to enter the expert configuration mode.

Forwarder Settings

When starting the module for the first time, see the dialog shown in Figure 24.1, “DNS Server Installation: Forwarder Settings”. In it, decide whether the PPP daemon should provide a list of forwarders on dial-up via DSL or ISDN (PPP Daemon Sets Forwarders) or whether you want to supply your own list (Set Forwarders Manually).

Figure 24.1. DNS Server Installation: Forwarder Settings

DNS Server Installation: Forwarder Settings
DNS Zones

This dialog consists of several parts and is responsible for the management of zone files, described in Section 24.4, “Zone Files”. For a new zone, provide a name for it in Zone Name. To add a reverse zone, the name must end in Finally, select the Zone Type (master or slave). See Figure 24.2, “DNS Server Installation: DNS Zones”. Click Edit Zone to configure other settings of an existing zone. To remove a zone, click Delete Zone.

Figure 24.2. DNS Server Installation: DNS Zones

DNS Server Installation: DNS Zones
Finish Wizard

In the final dialog, you can open the ports for the DNS service in the firewall that is activated during the installation and decide whether DNS should be started. The expert configuration can also be accessed from this dialog. See Figure 24.3, “DNS Server Installation: Finish Wizard”.

Figure 24.3. DNS Server Installation: Finish Wizard

DNS Server Installation: Finish Wizard

24.1.2. Expert Configuration

After starting the module, YaST opens a window displaying several configuration options. Completing it results in a DNS server configuration with the basic functions in place:


Under Booting, define whether the DNS server should be On or Off by default. To start the DNS server right away, select Start DNS Server Now. To stop the DNS server, select Stop DNS Server Now. To save the current settings, select Save Settings and Restart DNS Server Now. You can open the DNS port in the firewall with Open Port in Firewall and modify the firewall settings with Firewall Details.


This is the same dialog as the one opened after starting the wizard configuration (see Forwarder Settings).


This section allows you to set what the DNS server should log and how. Under Log Type, specify where the DNS server should write the log data. Use the systemwide log file /var/log/messages by selecting Log to System Log or specify a different file by selecting Log to File. In the latter case, additionally specify the maximum file size in megabytes and the number of log files to store.

Further options are available under Additional Logging. Enabling Log Named Queries causes every query to be logged, in which case the log file could grow extremely large. For this reason, it is not a good idea to enable this option for other than debugging purposes. To log the data traffic during zone updates between DHCP and DNS server, enable Log Zone Updates. To log the data traffic during a zone transfer from master to slave, enable Log Zone Transfer. See Figure 24.4, “DNS Server: Logging”.

Figure 24.4. DNS Server: Logging

DNS Server: Logging
DNS Zones

This dialog is explained for the wizard configuration. See Section 24.1.1, “Wizard Configuration”.

Slave Zone Editor

This dialog opens if you selected the zone type Slave in the step described in DNS Zones. Under Master DNS Server, specify the master from which the slave should fetch its data. To limit access to the server, select one of the ACLs from the list. See Figure 24.5, “DNS Server: Slave Zone Editor”.

Figure 24.5. DNS Server: Slave Zone Editor

DNS Server: Slave Zone Editor
Master Zone Editor

This dialog opens if you selected the zone type Master in the step described in DNS Zones. The dialog comprises several pages: Basic (the one opened first), NS Records, MX Records, SOA, and Records.

Zone Editor (NS Records)

This dialog allows you to define alternative name servers for the zones specified. Make sure that your own name server is included in the list. To add a record, enter its name under Name Server to Add then confirm with Add. See Figure 24.6, “DNS Server: Zone Editor (NS Records)”.

Figure 24.6. DNS Server: Zone Editor (NS Records)

DNS Server: Zone Editor (NS Records)
Zone Editor (MX Records)

To add a mail server for the current zone to the existing list, enter the corresponding address and the priority value. After doing so, confirm by selecting Add. See Figure 24.7, “DNS Server: Zone Editor (MX Records)”.

Figure 24.7. DNS Server: Zone Editor (MX Records)

DNS Server: Zone Editor (MX Records)
Zone Editor (SOA)

This page allows you to create SOA (start of authority) records. For an explanation of the individual options, refer to Example 24.6, “File /var/lib/named/”.

Figure 24.8. DNS Server: Zone Editor (SOA)

DNS Server: Zone Editor (SOA)
Zone Editor (Records)

This dialog manages name resolution. In Record Key, enter the hostname then select its type. A-Record represents the main entry. The value for this should be an IP address. CNAME is an alias. Use the types NS and MX for detailed or partial records that expand on the information provided in the NS Records and MX Records tabs. These three types resolve to an existing A record. PTR is for reverse zones. It is the opposite of an A record.

SUSE LINUX Administration Guide 9.3