UltraDNS is a subsidiary of NeuStar. UltraDNS offers managed DNS and traffic management services. UltraDNS claims their managed DNS solutions are "capable of processing thousands of queries per second".  Services offered by UltraDNS are mainly targeted towards companies and businesses rather than individuals, UltraDNS saying that they provide " solutions to organizations that rely on DNS for their critical business processes, applications and services, delivering superior security, reliability and performance." 
An article featured in the edition of Business Wire that appeared on July 31, 2000 mentioned UltraDNS as being the "First Company to Offer Outsourced Infrastructure Solutions for Large, Directory-Initiated Applications". 
UltraDNS provides DNS services to important names in the on-line industry like Oracle.com, LinkedIn.com, Myspace.com, Amazon.com, Gap.com, Diamond.com and others.
The company was not avoided by problems in its history, as on 31 May 2009 NetworkWorld reported that a number of important websites which used the services of UltraDNS, including Petco.com, Advertising.com, SalesForce.com and Amazon.com, experienced downtime of up to a couple of hours, due to a Distributed Denial of Service (D-Dos) attack.  A similar report appeared on the ZDNet blog.  This was quite a hit to the company as they claim that their services also "protect your customers’ Web operations from DNS-based DDoS attacks and pharming attacks from DNS cache poisoning. Our redundant infrastructure means no single point of failure."
- UltraDNS company overview
- DailyChanges UltraDNS page
- UltraDNS page on VentureBeatProfiles
- UltraDNS Corporation Formed To Lead Innovations In Services-Based Internet Infrastructure Solutions, Business Wire
- Some UltraDNS customers knocked offline by attack
- DDoS attack on UltraDNS affects Amazon.com, SalesForce.com, Petco.com
- UltraDNS on NeuStar