Configuring DNS Nameservers for DHCP
Many organizations use the MX appliance as a DHCP server, which will also configure hosts to use a specific DNS server. The MX offers four options for which DNS servers will be used:
- Proxy to upstream DNS
Clients will send DNS requests to the LAN interface of the MX, which will then proxy those requests to the DNS server(s) configured for its primary Internet uplink.
Please note the MX is capable of proxying up to 150 outstanding DNS queries at a time on 18.1 and earlier firmware. For use cases that require more than 150 concurrent queries, use a public or local DNS server
- Use Google Public DNS
Google maintains publicly available DNS servers. Clients will use 8.8.8.8 and 8.8.4.4 to resolve DNS.
- Use Cisco Umbrella
Cisco Umbrella uses the Internet's infrastructure to enforce security and block malicious activity before a connection is ever established. Umbrella provides additional services for their DNS, so pointing clients to their DNS servers allows those features to be used.
- Specify nameservers...
Specify the IP address of your DNS server to provide clients with custom DNS servers.
The following instructions outline how to configure custom nameservers for your MX's DHCP scope:
- On the Dashboard, navigate to Security & SD-WAN > Configure > DHCP > Main subnet/VLAN ID > DNS nameservers and choose Specify nameservers... from the drop-down.
- In the Custom nameservers field, enter the IPv4 address or hostname of your DNS server. You may specify additional servers with a new line, comma, or space.
- Click Save Changes.
The Custom nameservers field has a maximum character limit of 255.
