Knowledge Trail

Articles on networking, security and the web.

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  • · 12 min read

    How a device joins a network

    What happens in the first seconds after a device connects to a network, from getting an IPv4 address with DHCP and finding neighbors with ARP to configuring IPv6 with router advertisements, SLAAC, Neighbor Discovery and DHCPv6.
    Networking
  • · 15 min read

    How DNS works

    How the Domain Name System turns names like www.example.com into IP addresses, from the tree of domain names and the servers that hold them to caching, record types, message formats and security.
    NetworkingThe web
  • · 11 min read

    How email works

    How an email travels from one inbox to another, from the SMTP conversation between servers and the difference between envelope and header to MIME, mailbox access, and the SPF, DKIM and DMARC checks that fight forgery.
    NetworkingSecurity
  • · 16 min read

    How HTTP works

    How the Hypertext Transfer Protocol carries the web, from URLs, requests, methods and status codes to caching, cookies and the three versions in use today, HTTP/1.1, HTTP/2 and HTTP/3.
    The webNetworking
  • · 11 min read

    How internet routing works

    How the independent networks of the internet find paths to each other with the Border Gateway Protocol, from autonomous systems and AS paths to route selection, business relationships, route hijacks and leaks, and RPKI.
    Networking
  • · 20 min read

    How IP addresses work

    What an IP address identifies, how IPv4 and IPv6 addresses are written and divided into networks, which ranges are reserved, and how a packet travels from one address to another.
    Networking

Learning paths

  • 10 articles· 144 min

    Networking from the ground up

    Follow a web request from the bottom up, from how a device gets an address and its packets cross NAT and the routes of the internet, to DNS names, reliable TCP connections, TLS encryption, HTTP and the newer QUIC and WebSockets.
  • 4 articles· 48 min

    Security from the ground up

    Start with the mathematics of public and private keys, see how TLS uses them to protect every connection, then learn how websites store passwords safely and how OAuth lets apps act for you without ever seeing your password.

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