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Doing Horrible Things with DNS - Web Directions South
 

Doing Horrible Things with DNS - Web Directions South

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How can we make use of DNS to improve the performance of web sites? A simple introduction to DNS and a neat trick to improve web site performance using DNS.

How can we make use of DNS to improve the performance of web sites? A simple introduction to DNS and a neat trick to improve web site performance using DNS.

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    Doing Horrible Things with DNS - Web Directions South Doing Horrible Things with DNS - Web Directions South Presentation Transcript

    • Doing Horrible Things to DNS (in the name of science) @sh1mmer Yahoo! Inc
    • The basics of DNS
    • San Francisco - Mission Branch
    • San Francisco - Main Library
    • New York City - 5th & 42nd Branch
    • New York City - 5th & 42nd Branch
    • NYC San Francisco - Main Library
    • San Francisco - Main Library
    • NYC SF San Francisco - Mission Branch
    • San Francisco - Mission Branch
    • NYC SF Mission
    • NYC SF Mission Me
    • GTFO! It's 3am!
    • DNS for performance
    • Page Load Time vs. Bandwidth
    • Page Load Time vs. Round Trip Time
    • Trend Curves for Bandwidth vs. RTT
    • Serial HTTP loading - 1 domain
    • Parallel HTTP loading - 3 domains
    • So why not just use a loads of domains?
    • DNS Lookup
    • Ideal? 1 DNS query many parallel threads
    • Option 1: SPDY (by Google)
    • Good: Multi-thread TCP connections Bad: Only works on Chrome :(
    • Option 2: Do horrible things to DNS
    • Mucking about with C names
    • CNAMES are hosts which are aliases of other hosts
    • enki:~ $ dig yahoo.com ; <<>> DiG 9.4.3-P3 <<>> yahoo.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32801 ;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 7, ADDITIONAL: 7 ;; QUESTION SECTION: ;yahoo.com. IN A Query ;; ANSWER SECTION: yahoo.com. 5935 IN A 69.147.125.65 yahoo.com. 5935 IN A 72.30.2.43 yahoo.com. 5935 IN A 98.137.149.56 yahoo.com. yahoo.com. 5935 5935 IN IN A A 209.191.122.70 67.195.160.76 Response ... ;; Query time: 45 msec ;; SERVER: 202.171.190.10#53(202.171.190.10) ;; WHEN: Wed Oct 13 17:23:39 2010 ;; MSG SIZE rcvd: 345
    • ajax1.hackerhouse.org. 1800 IN CNAME ajax2.hackerhouse. ajax2.hackerhouse.org. 1800 IN CNAME ajax3.hackerhouse. ajax3.hackerhouse.org. 1800 IN CNAME ajax4.hackerhouse. ajax4.hackerhouse.org. 1800 IN CNAME ajax.hackerhouse. ajax.hackerhouse.org. 1800 IN A 192.168.1.1 ajax.hackerhouse.org. 1800 IN A 192.168.1.2 ajax.hackerhouse.org. 1800 IN A 192.168.1.3 ajax.hackerhouse.org. 1800 IN A 192.168.1.4 ajax.hackerhouse.org. 1800 IN A 192.168.1.5
    • We now have 5 hostnames with 1 DNS query
    • 5 hostnames x 6 request per host = 30 parallel requests
    • Doing Horrible Things to DNS (in the name of science) Questions? @sh1mmer Yahoo! Inc