Implementing Per-Domain DNS Configuration in macOS Using Resolver Configuration Files

In macOS, managing network traffic is essential for a robust and secure IT infrastructure. The operating system allows users to have a granular level of control over Domain Name System (DNS) settings, improving network functionality. Today’s post will walk through setting up per-domain DNS configuration on macOS using resolver configuration files.

Adding a DNS Rule Per Domain

MacOS has a powerful feature that allows you to specify DNS servers for individual domains. This is accomplished by creating resolver configuration files in the /etc/resolver/ directory. Each file in this directory corresponds to a domain and specifies the DNS servers to be used for that domain.

Let’s add a DNS rule for the “ymbihq.local” domain:

1. Open Terminal.
2. Use the sudo command to create a new file in the /etc/resolver/ directory with the same name as your domain:

sudo bash -c 'echo "nameserver 10.0.0.1" > /etc/resolver/ymbihq.local'

This command will create a new resolver file named ymbihq.local and adds a line specifying 10.0.0.1 as the nameserver. As a result, all DNS queries for “ymbihq.local” will be resolved by the DNS server at the IP address 10.0.0.1.

Reviewing DNS Rules

To verify that the resolver configuration file was created successfully and to review its content, use the cat command:

cat /etc/resolver/ymbihq.local

This will output the contents of the ymbihq.local file, which should look like this:

# Sample output:
nameserver 10.0.0.1

This confirms that the DNS server for the “ymbihq.local” domain has been set to 10.0.0.1.

Removing a DNS Rule

If you need to remove a DNS rule, you can simply delete the corresponding resolver configuration file. Use the rm command for this:

sudo rm /etc/resolver/ymbihq.local

After running this command, your macOS system will no longer have a custom DNS server set for the “ymbihq.local” domain, and it will default to using your standard DNS servers.

By creating and managing resolver configuration files, you can precisely control your DNS settings on a per-domain basis. This powerful feature of macOS allows you to optimize your network to fit your specific needs.