DNS: Create a Forward Zone

15 minutes
  • 5 Learning Objectives

About this Hands-on Lab

Zones and zone files are key components in configuring DNS servers. In this lab, we will configure a forward zone and a forward zone file, then add TTL, SOA, NS, and A records. Next, we will run a syntax check on the `named.conf` and the forward zone file with `named-checkconf` and `named-checkzone`, respectively. This allows a name server to resolve a query, given the hostname, and returns the IP address. This is the most common type of DNS query.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Add the forward zone configuration to the `/etc/named.conf` file. Then run the `named-checkconf` command to verify the configuration.
  1. Add the forward zone configuration:
    vim /etc/named.conf
    1. Insert the zone configuration just before the include statements at the bottom of the file:
      zone "mylabserver.com" {
      type master;
      file "/var/named/fwd.mylabserver.com.db";
      };
    2. Run the named-checkconf command to verify the configuration.
      named-checkconf
Create the forward zone file and check the configuration for syntax errors with `named-checkzone`.
  1. Create the forward zone file and enter the following information:
    vim /var/named/fwd.mylabserver.com.db
  2. Enter in the following:
    $TTL    86400
    @       IN      SOA     nameserver.mylabserver.com. root.mylabserver.com. (
                          10030         ; Serial
                           3600         ; Refresh
                           1800         ; Retry
                         604800         ; Expiry
                          86400         ; Minimum TTL
    )
    ; Name Server
    @        IN      NS       nameserver.mylabserver.com.
    ; A Record Definitions
    nameserver       IN      A       172.31.18.93
    mailprod         IN      A       172.31.18.30
    mailbackup       IN      A       172.31.18.72
    ; Canonical Name/Alias
    dns        IN    CNAME    nameserver.mylabserver.com.
    ; Mail Exchange Records
    @        IN    MX    10    mailprod.mylabserver.com.
    @        IN    MX    20    mailbackup.mylabserver.com.
  3. Run the named-checkzone command to check the zone file for syntax errors.
    named-checkzone mylabserver.com /var/named/fwd.mylabserver.com.db
Change the file permissions and the group owner for `/var/named/fwd.mylabserver.com.db`.
  1. Change the file permissions for /var/named/fwd.mylabserver.com.db:
    chmod 760 /var/named/fwd.mylabserver.com.db
  2. Change the group owner of the file to named.
    chgrp named /var/named/fwd.mylabserver.com.db
Restart the named service.
systemctl restart named
Run a query to test the configuration.
nslookup mailprod.mylabserver.com localhost

Additional Resources

ABC Company is currently in the process of setting up its own internally-hosted DNS service. The next phase of the project is to create the forward zone files. The DNS administrator fell sick and is unavailable, but the project has a tight timeline. We have been designated as a resource to create the forward zone files until the DNS Administrator returns.

To complete this lab, we need to use the vim command to create and open a forward zone file and create the following records:

  • TTL Record
  • SOA Record
  • A Records:
    • nameserver
    • mailprod
    • mailbackup
  • CNAME Record:
    • dns = nameserver.mylabserver.com.

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