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Take the former Veritas corporate web server as an example. A person using a web browser specifies the URL www.veritas.com to view the Veritas web page, where www.veritas.com maps to the canonical name mtv.veritas.com, which is a host in Mountain View running the web server. The browser, in turn, retrieves the IP address for the web server by querying the domain name servers. If the web server for www.veritas.com is failed over from Mountain View to Heathrow, the domain name servers need to be updated with the new canonical name mapping so that the web browsers are directed to Heathrow instead of Mountain View. In this case, the DNS agent should update the name server to change the mapping of www.veritas.com, from mtv.veritas.com to the canonical name of the standby system in Heathrow, hro.veritas.com, in case of a failover.