iRule to verify request to VIP came via a URL, not an IP

On the front VIP, you could add this iRule:

when HTTP_REQUEST {
  if { not ([stringtolower [HTTP::host]] ends_with "domain.com") } {
    reject
  }
}

This should work as long as anything "domain.com" is acceptable.

Yes. Something like this might work. Haven't tested it, but the theory is workable I believe.

Data group of allowed DNS hosts used to verify web address. ltm data-group internal /Common/ALLOWEDDNS { records { www.mycompany.com { } www.mycompany.net { } www.mycompany.org { } } type string }

iRule ltm rule /Common/RULE_NOIPS { when HTTP_REQUEST { if {[matchclass [HTTP::host] equals $::ALLOWEDDNS]} { pool MYWEBPOOL } else { reject } } }