OpenDNS earns a portion of its revenue by displaying advertisements on a search page shown when their system cannot automatically correct a domain name typo. OpenDNS claims it is not the same as Site Finder as it is purely an opt in service and that the advertising revenue pays for the customized DNS service.

According to OpenDNS, additional services that run on top of its enhanced DNS service will be provided, and some of them may cost money. These announcements have caused some users who are suspicious of OpenDNS’s agenda to drop the service.

One of the biggest criticisms is that OpenDNS removes the redundancy that traditional DNS offers. The traditional form of DNS relies on a decentralized collection of servers scattered throughout the world which offers a high level of redundancy. OpenDNS centralizes this system, making it more susceptible to failure.

Paul Vixie, in a message posted to a DNS Operations forum, criticized OpenDNS on several grounds, including the fact that it is limited to web surfing and that its centralization means a loss of privacy for its users.