Doing Horrible Things to DNS in the Name of Science - SF Performance Meetup

Doing Horrible Things

to DNS(in the name of science)

@sh1mmer SF Perf MeetupThursday, September 23, 2010

The basics of DNS

Thursday, September 23, 2010






San Francisco - Mission BranchThursday, September 23, 2010



San Francisco - Main LibraryThursday, September 23, 2010



New York City - 5th & 42nd BranchThursday, September 23, 2010



New York City - 5th & 42nd BranchThursday, September 23, 2010











DNS for performance


Page Load Time vs. BandwidthThursday, September 23, 2010

Page Load Time vs. Round Trip TimeThursday, September 23, 2010

Trend Curves for Bandwidth vs. RTTThursday, September 23, 2010

Serial HTTP loadingThursday, September 23, 2010

Parallel HTTP loadingThursday, September 23, 2010

Why not just use a bunch of domains?


DNS QueryingThursday, September 23, 2010

Ideal? 1 domain many threads


Option 1: SPDY


Good: Multi-thread TCP connections Bad: Only works on Chrome


Option 2: Do horrible things to DNS


Good: Works nowBad: Might have to violate RFCs


Option 2a - Mucking about with C names


CNAMES are hosts which are aliases of other hosts


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 ajax5.hackerhouse.ajax5.hackerhouse.org. 1800 IN CNAME ajax.hackerhouse.ajax.hackerhouse.org. 1800 IN A 127.0.0.1


We now have 6 hostnames


Good: 6 hostnamesBad: Inflexible


Option 2b - Doing weird things with RRs


RR is the section of a DNS response which contains the HOST records


;; QUESTION SECTION:;ajax.hackerhouse.org. IN A

;; ANSWER SECTION:ajax.hackerhouse.org. 60 IN A 184.106.231.91


;; QUESTION SECTION:;ajax.hackerhouse.org. IN A;ajax1.hackerhouse.org. IN A;ajax2.hackerhouse.org. IN A

;; ANSWER SECTION:ajax.hackerhouse.org. 60 IN A 184.106.231.91ajax1.hackerhouse.org. 60 IN A 184.106.231.90ajax2.hackerhouse.org. 60 IN A 184.106.231.89


;; QUESTION SECTION:;ajax.hackerhouse.org. IN A

;; ANSWER SECTION:ajax.hackerhouse.org. 60 IN A 184.106.231.91

;; ADDITIONAL SECTION:ajax1.hackerhouse.org. 60 IN A 184.106.231.90ajax2.hackerhouse.org. 60 IN A 184.106.231.89


Good: FlexibleBad: Caching /Violating RFCs


Technology

Doing Horrible Things to DNS in the Name of Science - SF Performance Meetup