Explaining the Comcast Internet outage
What happened to Comcast customers last night? Customers who experienced a two-and-a-half hour outage of Internet service technically did not experience an outage at all.
The problem, which affected customers in New England and Washington, D.C., was with Comcast's Domain Name System, or DNS.
It works something like the phone system. When you pick up a traditional telephone and hear the dialtone, you have to punch in the numeral one, the area code, and the phone number you want in order to make a connection.
The Internet works in a similar way. Every web site resides on a computer or part of a computer, including servers, and each computer has its own unique number to identify its place on the net. It's called an IP address, standing for Internet Protocol, and it serves something like a phone number.
The DNS is the phone book. When you type in Boston.com, your Internet Service Provider's DNS servers translate the name, which is easy to remember, into the Boston.com IP address, which is 220.127.116.11; not easy to remember.
When Comcast's DNS system went down, some computer-savvy customers knew to switch their computer to another set of DNS servers, which allowed them to connect to their Internet service.