Dud queries swamp US Internet Root servers

Security Alert [The Register]

Broken queries are swamping US Internet servers with unnecessary traffic. A detailed analysis of 152 million messages received on Oct. 4, 2002 by one of the root servers in California showed that only 2 per cent of the queries were legitimate.

The Cooperative Association for Internet Data Analysis (CAIDA) at the San Diego Supercomputer Center (SDSC) which conducted the research is trying to understand why the roots get so many broken queries from Internet service providers.

DNS root servers provide a critical service to Internet users by mapping text host names to numeric Internet Protocol (IP) addresses. The 13 roots are operated by a mix of volunteers and U.S. government agencies. The U.S. Department of Commerce is the agency responsible for managing the root system which serves most Internet users.

“If the system were functioning properly, it seems that a single source should need to send no more than 1,000 or so queries to a root name server in a 24-hour period,” said CAIDA researcher Duane Wessels. “Yet we see millions of broken queries from certain sources.”

CAIDA researchers speculate that 70 per cent of the bad requests are due to misconfigured packet filters, firewalls, or other security mechanisms intended to restrict network traffic. Twelve per cent of the illegitimate traffic however could not be explained and was for nonexistent top-level domains, such as “.elvis”, “.corp” and “localhost”.

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