Using an HTTP header field group in a Layer 5 content rule enables a rule to be more specific than if the rule just defined a URL. The HTTP header field group makes the content match more specific. Because content rules are hierarchical, if a request for content matches more than one rule, the characteristics of the most specific rule apply to the flow. This hierarchy for Layer 5 rules is defined below. The CSS uses this order of precedence to process requests for the content, with 1 being the highest match and 4 being the lowest match.
Domain name, IP address, protocol, port, URL, HTTP header field group
IP address, protocol, port, URL, HTTP header field group
Domain name, protocol, port, URL, HTTP header field group
Protocol, port, URL, HTTP header field group