The DNS64 prefix is an IPv6 address prefix used by Zscaler's purpose-built DNS64 mechanism to synthesize AAAA records from A records returned for servers that can be reached via IPv4. Zscaler facilitates the DNS64 mechanism with its own default IPv6 prefix and the well-known prefix (64:ff:9b::/96), without requiring any additional configurations by Internet & SaaS administrators. However, organizations can configure and use their network-specific DNS64 prefixes instead of the default prefixes supported by Zscaler. You can designate one of the configured NAT64 prefixes as the DNS64 prefix for your organization. You can also configure a DNS64 prefix for individual locations and override the global DNS64 prefix for those locations. For more information, see Configuring Locations.

DNS64 prefix selection by Zscaler from the prefixes available at different sources follows a specific order, as explained in the following bulleted list:

1. Zscaler Client Connector-Shared Prefix
2. Customer-configured prefix for a location in the Admin Portal
3. Customer-configured prefix for an organization in the Admin Portal
4. Zscaler's default prefix for the cloud on which your organization is provisioned
5. Well-known prefix for NAT64 (64:ff9b::/96)

To learn more, see Understanding IPv6 Support.

About the DNS64 Prefix page

On the DNS64 Prefix page (Infrastructure > Internet & SaaS > Traffic Forwarding > IPv6 Configurations > DNS64 Prefix), you can do the following:

1. Configure DNS64 prefix at the organization level.
2. View the DNS64 prefix configured at the organization level. You can view:
   • Name: The name of the DNS64 prefix.
   • Prefix/Mask: The DNS64 prefix and the subnet mask for the prefix.
   • Description: The description of the DNS64 prefix.
3. Edit the DNS64 prefix.
4. Modify the table and its columns.
5. Search for a DNS64 prefix.
6. Go to the NAT64 Prefixes and Settings pages.