Which expression correctly matches the host name www.example.com in all HTTP requests?

• A. HTTP.REQ.HOSTNAME.EQ("www.example.com")
• B. HTTP.REQ.HOSTNAME.CONTAINS("www.example.com")
• C. HTTP.RES.HOSTNAME.EQ("www.example.com")
• D. HTTP.REQ.HOSTNAME.EQ("example.com")

Answer: (D)

The expression should check the Host header coming with the HTTP request, using the request hostname value. To match every request aimed at www.example.com exactly, you compare the hostname directly to the full host name, including the www subdomain. This exact match is the most reliable way to ensure only requests for that specific host are matched, since the Host header in standard HTTP requests will be www.example.com for that site.

Using the response hostname would look at data sent back by the server, not at what the client requested, so it’s not appropriate for matching incoming requests. Matching with a broader test like contains would be less precise and could inadvertently match other hostnames that include the string. Therefore, an exact equality check against www.example.com is the correct approach.