In Microsoft Internet Information Services (IIS) 6.0, when a request contains a header name that includes a question mark (?) character or another separator character, Http.sys rejects the request and sends the following error message to the requestor: Bad Request (Invalid Header Name). Additionally, when you use lowercase HTTP verbs like "get," Http.sys rejects the request and sends the following error message to the requestor: "Bad Request (Invalid Verb)".