Comcast Internet Outage Affects Chicago Area, NW Indiana and More: Started Sunday 7:30 p.m., Restored Midnight

Comcast customers in Arlington Heights, Chicago, Northern Illinois, Northwest Indiana, Southwest Michigan and Minnesota were affected by an issue with their DNS servers. The issue caused customer computers, laptops, iPads, iPhones operating via wireless routers, and wireless routers themselves to be unable to resolve a web address or domain name.

People who typed in a web address watch with their browsers pause, instead of reaching the desired web address. They eventually got a message that the host server was not available.

Arlington Heights Comcast Internet service was restored at midnight. Some areas were reported earlier or later than midnight.

DNS servers translate humanly memorable domain names (,, and hostnames (where ‘en’ is the local host name of into the corresponding numeric Internet Protocol (IP) addresses, the second principal Internet name space, used to identify and locate computer systems (e.g., the servers that hold Facebook information) and resources (web cams, other sensor) on the Internet. Root name servers are maintained by delegation by the Internet Corporation for Assigned Names and Numbers (ICANN). Records are propagated constantly to DNS servers around the world. For example, when a new domain name is created, the record created to allow access to that domain name or web address needs to propagate from the root servers to domain name servers around the world. Comcast DNS servers were not functioning at some level.

The problem is not with transmission lines, amplifiers or cable lines. The problem is an issue with DNS servers not able to bring customer’s request for a domain name to the actual host that is serving the files for that domain name.

It is unknown if Comcast was under a hacker’s attack on the DNS servers, or if Comcast was performing a maintenance upgrade, or if their was some type of unexpected equipment failure.

Customers were able to get around the DNS problem by using Google Public DNS ( and … see Using Google Public DNS) or ( and … see

The workaround involved changing the network settings of the computer or changing the settings of network routers. If computers at home were setup on a wireless network router or used a regular router, the settings on the router needed to be changed — a little more difficult to do than changing the settings on a computer.

Mobile users who used their devices, such as iPhones, iPads, Droids, Blackberries via their wireless providers did not experience an outage. However, mobile users who were connected via their home wireless networks connected to Comcast were affected by the outage.

MI and IN should start getting back online and others should be on shortly as well
— Twitter message from comcastcare just before midnight CST

Comcast customer service was updating customers via its twitter account …

Customers calling 1-800-Comcast during the outage either got a busy signal or were greeted by a recorded message saying that the company was experiencing technical difficulties with instructions to call back later.



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