Multiple Domains using one address

[Michael Garabaldi]

Newbie:

Is it valid to have multiple domains using the same A records and PTR
records? That is:

www.mydomain1.com  IN  A 206.110.20.30
www.mydomain2.com  IN  A 206.110.20.30
www.mydomain3.com  IN  A 206.110.20.30


30.20.110.206.IN-ADDR.ARPA.     PTR   www.mydomain1.com
30.20.110.206.IN-ADDR.ARPA.     PTR   www.mydomain2.com.
30.20.110.206.IN-ADDR.ARPA.     PTR   www.mydomain3.com

If this is valid, are there any pitfalls I should know about? TIA!