I-D ACTION:draft-pappas-dnsop-long-ttl-02.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: Improving DNS Service Availability by Using Long TTLs
	Author(s)	: V. Pappas, et al.
	Filename	: draft-pappas-dnsop-long-ttl-02.txt
	Pages		: 22
	Date		: 2006-6-27

Due to the hierarchical tree structure of the Domain Name System
   [RFC1034][RFC1035], losing all of the authoritative servers that
   serve a zone can disrupt services to not only that zone but all of
   its descendants.  This problem is particularly severe if all the
   authoritative servers of the root zone, or of a top level domain's
   zone, fail.  Although proper placement of secondary servers, as
   discussed in [RFC2182], can be an effective means against isolated
   failures, it is insufficient to protect the DNS service against a
   distributed denial of service attack (DDoS).  This document proposes
   to mitigate the impact of DDoS attacks against top level DNS servers
   by setting long TTL values for NS records and their associated A
   records.  Our proposed changes are purely operational and can be
   deployed incrementally.  Our analysis shows that this simple
   operational tuning has a small impact on DNS performance but can
   significantly reduce the impact felt by client resolvers as a result
   of a successful DDoS attacks on the DNS service.

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