How the Outages Happened

The Domain Name System (DNS) is an integral part of the Web’s infrastructure, allowing users to enter easy-to-remember URLs (like www.microsoft.com) instead of more complex IP addresses (like 255.108.77.144). In normal circumstances, the process works as follows:

1. The user types in a specific URL, e.g., www.microsoft.com. The browser forwards this request to a name server. Although this first name server can be anywhere on the Internet, it is often a local name server, located within a user’s corporate infrastructure or ISP.

2. The first name server forwards the request to a root level name server. In the United States, these are operated by the Internet Network Information Center (InterNIC), a cooperative venture between the United States government and various registrar companies (the largest registrar company-and formerly the exclusive one-is Network Solutions).

3. The root level server checks the request against a registry of all possible domains and determines the IP address of the primary name servers that contain information about the domain microsoft.com. It sends IP addresses of these name servers back to the first server.