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Off-campus recursive DNS access to be disabled

The following change does not impact computers, routers and devices on the Carnegie Mellon network.

DATE: Wednesday, May 29, 2013

USERS IMPACTED: Users who have specifically configured their off-campus computer or router to use SCS DNS servers for all domain name lookups


On Wednesday, May 29, 2013, SCS Computing Facilities will reconfigure the site caching name servers so that they will no longer accept recursive DNS queries from off campus. After this date, machines which are configured to use the SCS caching name servers will no longer be able to perform DNS lookups when not located on the Carnegie Mellon network.

This change is necessary in order to prevent our DNS servers from being used in denial of service (DoS) attacks on third-party networks by persons outside of Carnegie Mellon.

Machines supported by SCS Computing Facilities will not be affected by this change. In addition, this change has no effect for machines which are properly set to obtain DNS server configuration from DHCP, or which run full-service resolvers which do not depend on an external cache. These settings are the defaults in current versions of Windows, Mac OS X, and all major Linux distributions. This change will also have no effect for machines located on Carnegie Mellon's network, even if not properly configured.

To verify that your computer will not be affected, please see the following help page:

Please contact the SCS Help Desk at x8-4231 or send mail to if you have any questions regarding this change.

Thank you for your attention,

SCS Help Desk