March 30, 2019

stuff I do not know

In the spirit of a Feynman notebook, here’s my current list of things I do not know and want to learn.


  • What is erasure coding? (basics 2019/03/11)
  • What hashing algorithms are used for erasure coding?
  • What is backtesting?


  • How can I understand the Lagrange operator? (writeup forthcoming)
  • What is a unitary matrix? (writeup forthcoming)


  • How does DNS work? (intro learning 2019/03/07)
    • What is an SOA record in DNS?
  • How do data center internal networks connect to the public Internet?
  • What’s the right way to intuit CIDR notation?
  • What are the OSI network layers and how do they interact? (intro learning 2019/03/08)
    • What is a MAC address and how is it used? (writeup forthcoming)
    • What is Logical Link Control (LLC) and how is it used?
    • ~~ What are the four layers to the TCP/IP stack?~~ (writeup forthcoming)


  • What is an itable in computer language design?
  • How do you sign an XML document (eg. for SAML)?
  • What are the TPC-DS benchmark queries?
  • What’s different about geospatial databases and queries? ( I got a good answer, but forgot to write it up, and now I forgot the answer! )
  • What are good replacements for DynamoDB in other cloud providers?
  • What is a service mesh?
  • How does one determine why a CloudWatch Event Rule Invocation failed?
  • What’s the correct approach to handling many protocol buffer definitions?


  • What, really, is the mathematics behind RSA encryption?
  • Which are all the RSA encryption protocols?
  • How does SAML work? (intro learning 2019/03/07)
    • what is a X.509 certificate? (very basic intro 2019/03/08)
    • What is the TLS/SSL protocol?
    • Why are there Certificate Authorities?
    • When and why should I sign my own SSL certificate?
    • What are other uses of X.509 certificates?
    • What are the file extensions .pem, .cer, etc for?
    • how can “serverless” applications manage SAML SSO?


  • How did Rawanda recover from civil war and genocide?
  • When did Honduras and Guatemala split from Mexico and why?
  • What’s the relationship between Mayan and Chinese language?
  • What’s it like to live in a city with more than 50% of the economy from tourists? ( I should finish writing about Cairns, Australia )


  • How do the mangroves drink salty water? ( I learned in Ishigaki, Japan, that the mangroves isolate the salt content in a few leaves, which then fall off, allowing the plant to “drink” the fresh water from the desalinification )
  • Why did the Ice Age end?
  • How much photosynthesis is required to keep CO2 levels at 400ppm?
  • How do you estimate photosynthesis activity by photographic evidence?

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