Moving IIS hosting.asp redirects to iRules

Depending on how many redirects there are you could use either a case select or a datagroup.

With the datagroup, create one with a name of the site and the value as the URi you want to redirect to then use an iRule similar to below.

when HTTP_REQUEST { HTTP::redirect [class lookup [HTTP::host] datagroup1] }

If you only have a couple to do you may want to use a case select switch statement.

switch [URI::query [HTTP::host]] {
   option1 { set selected_node uri1 }
   option2  { set selected_node uri2 }
   }
    HTTP::redirect selected_node

    or of course you could have the redirect in the switch statement, it depends if you want to use the URI later on for logging etc.. or to make it easier to read.