I am impressed with the OpenDNS service, and I use it where ever possible. I have ran into a small problem in using OpenDNS. When using it with heavy traffic applications such as Microsoft Exchange or a Microsoft SQL database you can run into connection issues. It might be intermittent connections or some cases no connection at all.
There is the theory presented on this forum. I have also suspected that the small routers are unable to handle the large amount of DNS requests quickly enough.
There are two ways to correct this problem.
1. Static IP addresses. You can set each computer on the network to a static IP address and static DNS pointing to OpenDNS. This solution works well enough for small networks. The problem can be managing IP addresses on large networks. It is not effective if you have notebook computers that travel off of the network. Be sure to pick IP addresses that will not conflict with the addresses served by your DHCP server. An example would be to start your DHCP server at x.x.x.100, and then place any static addresses below that address.
2. More robust DHCP server. Setup your server to serve DNS and assign IP addresses using DHCP. This will also alleviate the problem as well as give you a more robust and customizable DHCP server.
In a later post we will go into options for setting up a DHCP server.