How To Fix “Host dns.lan not found: 3(NXDOMAIN)” Error in Bind9 DNS Server

The “Host dns.lan not found: 3(NXDOMAIN)” error is a common issue that system administrators encounter when working with Bind9 DNS servers. This error indicates that the DNS server is unable to resolve the hostname “dns.lan”. In this article, we will walk you through the steps to troubleshoot and fix this issue.

Check the DNS Configuration

The first step in resolving this error is to check the DNS server’s configuration.

Step 1: Ensure that the DNS server’s IP address is correctly specified in the /etc/resolv.conf file on the machine where you are running the host or nslookup command. You can check this by running:

cat /etc/resolv.conf

This command displays the contents of the resolv.conf file, which should contain a line like nameserver 192.168.1.5, where 192.168.1.5 is the IP address of your DNS server.

Step 2: Verify that the DNS server is running and accessible on the network. You can do this by pinging the server’s IP address:

ping 192.168.1.5

Step 3: Check the configuration files in the /etc/bind directory. The named.conf.options file should specify the correct forwarders (other DNS servers that Bind9 can use to resolve queries), and the named.conf.local file should define the correct zones (domains that Bind9 is responsible for).

Verify the Zone Configuration

The next step is to verify that the zone for the “dns.lan” domain is correctly configured.

Step 1: In the named.conf.local file, check that the zone “dns.lan” is defined and that the path to the zone file is correct. The zone definition should look something like this:

zone "dns.lan" {
 type master;
 file "/etc/bind/zones/db.dns.lan";
};

Step 2: Check the zone file (db.dns.lan) to ensure that it contains the correct DNS records for the “dns.lan” domain. The file should contain an SOA record at the beginning and NS and A records for the “dns.lan” domain.

Check the Reverse DNS Configuration

Reverse DNS is used to map IP addresses back to hostnames. If it is not configured correctly, it could be the cause of the “Host dns.lan not found: 3(NXDOMAIN)” error.

Step 1: In the named.conf.local file, verify that the reverse zone is defined correctly. The reverse zone definition should look something like this:

zone "1.168.192.in-addr.arpa" {
 type master;
 file "/etc/bind/zones/db.192";
};

Step 2: Check the reverse zone file (db.192) to ensure that it contains the correct PTR records for the IP addresses in the 192.168.1.0/24 subnet.

Verify the DNS Resolution Order

The DNS resolution order, specified in the /etc/resolv.conf file, determines which DNS servers are queried first. If the order is incorrect, it could lead to the “Host dns.lan not found: 3(NXDOMAIN)” error.

Ensure that the resolv.conf file has the correct order of DNS servers. It should start with the IP address of your DNS server (192.168.1.5) and then include other servers as failover.

Test with the dig Command

The dig command is a powerful tool for testing DNS resolution. Instead of using host or nslookup, try using dig to directly query the DNS server:

dig dns.lan @192.168.1.5

This command sends a DNS query for the “dns.lan” domain to the server at 192.168.1.5. If the server is configured correctly, it should return an A record with the IP address of “dns.lan”.

By following these steps and ensuring the correct configuration of the DNS server, zones, and DNS resolution order, you should be able to resolve the “dns.lan” hostname successfully. If you’re still encountering issues, consider seeking assistance from online communities like Stack Overflow or Server Fault.