On February 5, 2014, GCI is going to restrict our GCI’s caching DNS servers to networks where GCI provides Internet service.
In the past GCI has kept our Domain Name caching servers (220.127.116.11 and 18.104.22.168) open, which meant non-GCI subscribers could use our caching DNS servers.
GCI has seen an increase in the number and scale of a specific type of Internet Denial of Service (DoS) attacks called DNS Amplification attacks. This increase has reached a level of concern for GCI administrators, and is beginning to impact our normal customers. These attacks have not been directed at GCI, however GCI DNS servers are tricked into participating in the attack against other Internet addresses. These attacks result in a significant increase in bandwidth increasing the load on GCI servers, but causes slowdowns for GCI customers using the Internet.
There is no way to prevent these attacks, as they take advantage of the very nature of DNS servers. To decrease the impact, GCI is going to implement industry standards of restricting access to GCI’s DNS servers to GCI subscribers, commercial, broadband or customer owned networks that GCI routes. Any network where GCI provides Internet service should not be impacted by this change.
GCI apologizes for any inconvenience this change may create, however, the configuration changes are necessary to ensure GCI’s quality service to all our customers.
What do I need to do?
Most GCI customers will not see any change, nor need to take any action as a result of this change.
Corrective Action: Set DNS server settings to DHCP.
If you hard code your network connection to GCI’s servers and take that computer off of GCI’s network, you will receive an Internet connection error. Corrective action is to remove the hardcoding and set the devices DNS to DHCP. This will allow you to connect to the Internet via the Internet Service Provider (ISP) you are currently in.
There are no other corrective actions.