> ## Documentation Index
> Fetch the complete documentation index at: https://docs.domino.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Access additional domains and hostnames

Use custom DNS name servers to handle internal or private domain names and URLs. This topic describes how to add a new DNS server to your [Domino Environment](/cloud/platform-capabilities/core-concepts/compute-environments/manage-compute-environments) to allow access to additional domains and hostnames.

On a Linux host like your Domino executor, a configuration file at `/etc/resolv.conf` controls which DNS servers will be used to resolve hostnames. You can use a pre-setup script in your Domino Environment to modify this file and add custom DNS servers by following these instructions.

1. Open the Environment you want to modify, then click **Edit Definition**.

2. Scroll down to the bottom of the definition, then click to expand the **Advanced** section.

3. In the **Pre Setup Script** field, enter the following lines of Bash. Fill in the address of the custom server you want to use where indicated.

   ```bash theme={null}
   echo 'nameserver your-custom-server-address' > /tmp/resolv.conf.tmp
   cat /etc/resolv.conf >> /tmp/resolv.conf.tmp
   cat /tmp/resolv.conf.tmp > /etc/resolv.conf
   ```

4. Click **Build** at the bottom of the definition page to create a new version of the Environment.

Following a successful build, you can use this Environment to reach hosts through the added DNS name server.