This paper describes the design and performance study of our DNS-based portability solution. We present a design that extends the functionality of the basic DNS that enables the DNS to track the locations of its hosts. Unlike other solutions that simply update the hosts' latest IP addresses into their home domain zone files, our solution allows the locally assigned IP address to be updated into the local domain's DNS. This has the advantage of relieving the home DNS server from updating signaling load incurred when the mobile host changes its point of attachment between foreign domains. Our updating protocol overhead per message was also shown to be smaller in size than that of DNS dynamic update. Our scheme also exhibits smaller update delays.