iRule v11 to send user to correct DC database based on HTML header

HTTP::redirect "[HTTP::uri]"

HTTP::uri is not valid in HTTP_RESPONSE. you may have to save it to variable in HTTP_REQUEST and use the variable in HTTP_RESPONSE.

HTTP::retry -reset "GET [HTTP::header location] HTTP/1.1\r\nHost: $host\r\n\r\n"

you may need to check whether protocol (e.g. and hostname are included in HTTP::header location. if yes, you have to extract only uri part here.

If a HTTP::redirect is coming from LTM1 VIP to LTM2 VIP, would it come in as a HTTP_REQUEST or HTTP_RESPONSE?

you mean LTM2, don't you? if yes, i understand it will trigger HTTP_REQUEST on LTM2.

do you think the defualt 302 (Found - non-cacheable) HTTP:redirect code will be better then using "HTTP::respond 301 Location" (Moved Permanently)

i am not sure about this.

For Option 2, do I have to put in a variable for the default pool?

you are not using pool command in option2, are you?