Rod Beckstrom, the president and CEO of the Internet Corporation for Assigned Names and Numbers (ICANN), said Tuesday that he will leave the agency after his three-year term expires in July 2012.

It's been a tough job. ICANN is responsible for managing the IP addresses used to identify computers on the network, and it is also the ultimate authority on the top-level domains that humans use to surf the Web and send e-mail.

ICANN was spun out of the U.S. Department of Commerce, which managed the Internet from its early days until the late 1990s. Because ICANN is the ultimate authority over domain name registrations, it is often under pressure to clean up spammers and criminal activity on the Internet, something it has been slow to do.

Under Beckstrom, ICANN did focus on Internet security, primarily through pushing a new, more secure domain name system called DNSSEC. According to ICANN, now have the ability to use this system.

Beckstrom also available on the Internet.