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codns_osdi_04 - CoDNS Improving DNS Performance and...

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12/09/11 OSDI '04 1 CoDNS: Improving DNS Performance and Reliability via Cooperative Lookups    KyoungSoo Park , Vivek Pai, Larry Peterson,  Zhe Wang Princeton University
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12/09/11 OSDI '04 2 Domain Name System(DNS) Human-friendly names   IP addresses Operational for over 20 years Essential part of the Web Two components Server-side: name owners Client-side: contacting name owners
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12/09/11 OSDI '04 3 Two Kinds of DNS Problems Server-side problems   [Danzig92], [Jung01] Nameserver bugs Misconfigurations Hardening/replacing server infrastructure Client-side problems Between local nameservers (LDNS) and clients Larger memories = higher LDNS hit rate LDNS cache hit rate : 80 ~ 90% Result: LDNS problems magnified
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12/09/11 OSDI '04 4 Contributions Measure LDNS problems, causes Client-side DNS helper, CoDNS Communicates with other CoDNS peers Incrementally deployable Works with all DNS lookups (CDN, etc) Benefits Latency reduction: 27-82% Availability: generally adds extra ‘9’
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12/09/11 OSDI '04 5 Local DNS Lookup Problems Local DNS lookup failures 5+ seconds delay for cached records Frequent & widely-distributed Unpredictable service Directly affects user-perceived latency Random delays in web access Kills HTTP proxies, web services, and busy  mail servers
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12/09/11 OSDI '04 6 Demonstrating Local Problems Local name lookup every 6 seconds    “yyy.domain” on xxx.domain at 200 sites “planetlab-2.cs.princeton.edu” for  planetlab-1.cs.princeton.edu Lookup should be handled locally LDNS is site-shared, NOT PlanetLab’s Failure criteria 5+ seconds of latency  zero answer Rolling average of the past 100 queries
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12/09/11 OSDI '04 7 Expected DNS Behavior University of Utah  Rice University
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12/09/11 OSDI '04 8 DNS Failure on Various Nodes Cornell Texas A&M University of Oregon
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