Below is the required regex to validate any domain name, its simple so you can modify if you need to extend it.
^((http|https):\/\/)?([a-zA-Z0-9_][-_a-zA-Z0-9]{0,62}\.)+([a-zA-Z0-9]{1,10})$
^((http|https):\/\/)?([a-zA-Z0-9_][-_a-zA-Z0-9]{0,62}\.)+([a-zA-Z0-9]{1,10})$