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Last active January 24, 2022 09:13
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Topics to understand in TCP/IP networking
  • What is encapsulation
  • Link layer
    • Link layer basics (pick something like Ethernet to get a quick overview of what the link layer entails)
    • What is a MAC address
  • IP - this is a vast topic but there are several important concepts to understand here
    • IP addresses and subnet masks
    • How are IP addresses different from MAC addresses and why are they required
    • How do you discover a MAC address of a device on the same network if you only have its IP address (hint: see ARP)
    • What are routers and how IP routing works
    • Route tables
    • IP fragmentation
    • TTL
    • How ping and traceroute work
    • IPv6, why its required and why has its adoption been slow
  • Transport layer
    • What is a port number and why is it required
    • UDP
    • TCP
      • Connection establishment (three way handshake)
      • Connection termination
      • Data transfer
      • Reliable transmission
      • Flow control (sliding window)
      • Congestion control
      • Error detection
      • Maximum segment size (MSS) and its relation with IP fragmentation
      • Selective acknowledgements (SACK) and how they help
      • When should you use TCP instead of UDP and vice versa?
  • DNS
    • How it works - does it use UDP, TCP or something else?
    • What are root name servers and how do DNS resolvers works starting from the root
    • What is the nameserver (NS) of a domain?
    • Different types of records
      • A
      • AAAA
      • CNAME
      • MX
      • TXT
      • NS
    • DNS-over-HTTPS and why browsers have started using it
  • HTTP
    • Request
      • Request line (method + path + query params + HTTP version)
      • Headers
      • Body
    • Response
      • Status line
      • Headers
      • Body
    • Safe methods v/s idempotent methods
    • When to use GET vs POST vs PUT
    • Cookies
    • Authentication
    • Content types
      • application/x-www-form-urlencoded
      • text/html
      • text/plain
      • application/json
      • Content types for images and other documents
    • Multi part requests
    • Chunked encoding
    • Compression
    • Why is the Host header required?
    • Connection re-use and request pipeline
    • Overview of HTTP/2 and HTTP/3
  • TLS
    • No need to go into details of TLS but understand the basics
    • What are X509 certificates and how does a client use them and a certificate authority to authenticate the server
    • What is asymmetric encryption and how it is used in TLS
    • What is Diffie Helman key exchange
    • When does symmetric encryption (like AES) come into play in a TLS connection
    • SNI
  • HTTP
    • Understand the relationship between TCP, TLS and HTTP - especially how HTTP is built on top of TCP/TLS and the guarantees that the underlying protocols provide (e.g. stream of bytes, etc.)
    • What is HTTP proxying and how it works
    • CDNs and how they reduce network latency
  • HTTPS
    • Difference between HTTP and HTTPS
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