A DNS error is basically your web browser, or some other 

Internet-enabled application, saying "Hey, I tried to find something 

online, but nobody responded to tell me where it is." You usually can't tell from the error how a DNS server responded, or where the point of failure is. Domain Name Service is the technology that translates the website address you type in your browser to an actual web address number that your computer and Internet service can understand. Without DNS you would have to type the actual IP address for each website you wanted to locate.  

On most business networks, troubleshooting DNS can be complicated by multiple devices providing DNS. For example, a typical business network may include an interface to the ISP (Internet Service Provider), a router that provides that Internet connection to the LAN and a Windows 2xxx file server. The way that sort of network is typically set up, the Windows file server provides DNS to the clients, but it stores mostly local DNS information on it. It forwards Internet DNS requests up to the router. The router also stores very little DNS information; it, in turn, forwards DNS requests along to the ISP, whose DNS servers shoulder most of the task of providing Internet DNS translation. A failure anywhere along the line will result in a DNS error. The network troubleshooter has to figure out where that failure might be.  

 

So, why all this forwarding? Why not just distribute the ISP's DNS 

address to the clients and let them go right to the source, as it were?  Because if you do that, then local file and printer sharing becomes much harder to manage, and, if it is NOT managed, it breaks down completely.  You need a local DNS server to direct your print jobs to your office printer or use friendly names to use shared hard drives. Without it, you would have to do all these tasks by IP address, which means anything sharing something on your network would need a static IP address, which you'd then have to keep track of and update on every client whenever one has 

to change.

Before you begin any troubleshooting it's important to confirm who owns and who manages the routers on your network. This may sound simple but check carefully. Do you really own that Netopia router or is AT&T supplying it? Are they managing it? If AT&T owns it, then they own the DNS problem no matter whether it's local, a line problem or a problem with their DNS servers. If you, the customer, owns the Internet router, then you have to troubleshoot the device enough to rule out a problem which will probably mean you need to replace it before you lean on AT&T for help. 

 
Note from RAM . . .

The solution might be as simple as updating an out-of-date DNS address on a router on your network. But how do you, the customer, know this is the case? Your best bet is to keep an inventory of all your devices that help provide Internet to your users. Determine which ones you manage and which ones the Internet provider is responsible for. If a DNS error occurs, you or your end users should receive an error message on the screen. Write down this error message and forward it to your IT Pro for help. If you don't have a dedicated professional to help you please contact RAM today. We can provide several recommended vendors to you including Mark who are happy to help.