The ValidateUrl method will check the value of a
string to ensure that it represents a complete, valid URL using
either a standard or secure HTTP scheme. This method will not
establish a connection with the server to verify that it exists,
it will only attempt to resolve the host name to an IP address.
If the remote host is specified as an IP address, this method
will check to make sure that the address is formatted correctly.
Note that if you wish to specify an IPv6 address, you must
enclose the address in brackets.
Unlike the URL property, this method will not throw an
exception if the specified URL is invalid.