Domain labels let you group related domains under a single name for easier configuration. You can use wildcards and host labels within these groupings. They are especially useful for setting up rules for domains that share similar optimization settings.

Domain labels are compatible with autodiscover, passthrough, and fixed-target in-path rules (not packet mode), but they don't work with connection forwarding or QoS rules. Starting with RiOS 9.16.0, domain label subnets also support IPv6.

It’s important to note that domain labels do not replace destination IP addresses. In-path rules still require destination matching by IP, subnet, port, port label, or host label. The appliance first matches the destination, then checks the domain label. Both conditions must match for the rule to apply.

Since domain labels only apply to HTTP and HTTPS traffic, if you set the destination port to "All," the rule defaults to ports 80 (HTTP) and 443 (HTTPS). If you need to optimize other ports, choose the "Specific Port" option instead.

Be aware that fixed-target rules using domain labels take precedence over autodiscovery. If a fixed-target rule with a domain label matches a SYN packet, the traffic won't use autodiscovery—it will pass through instead.

A domain can be included in multiple domain labels, and you can define up to 63 unique domain labels.

When using domain labels in in-path rules with cloud acceleration enabled, connections to the subscribed cloud platform are passed through to that platform by default. However, you can optimize cloud traffic across other appliances in your network by creating specific in-path rules.

To do this, create an in-path rule where Cloud Acceleration is set to Auto, and specify the SaaS Application host label. This allows the system to automatically determine whether to optimize the traffic or pass it through to the cloud service.

For proper rule matching, make sure that in-path rules using domain labels are placed lower in the rule list than the cloud acceleration rules. This ensures the system evaluates and applies cloud acceleration rules first before checking for domain label matches.