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What happens when you go to google

DNS

  • Check the cache
  • Google.ca.
  • Root authority
    • 100 IP addresses hardcoded on browser/devices
  • Tells you where the CA root server is
  • CA root server tells you what google.ca IP address is
    • One of Google's load balancers

Load balancer

  • Server that's setup to handle a ton of requests
  • Redirects those requests to web servers

TCP/QUIC handshake

  • Establish a connection with the google server via the load balancer
  • Syn syn ack
    • With the load balancer
    • Which already has sessions with a bunch of Google servers
  • Second handshake to establish TLS (HTTPS)
  • QUIC protocol does both handshakes at the same time
  • Every request will now have a cookie

HTTP GET request

  • Google sends us an HTML page
  • It might even be a cached page (on Google's end) if you're not logged in

Downloading/Reading the HTML page

  • See the Network tab in the browser
  • Chrome can stream HTML
    • Read the HTML as it comes in
  • Reads the HTML

    - Requests additional resources like the CSS and JS in the link and script tags

Renders the HTML page

  • See the Performance tab
  • Calculates the DOM from HTML
    • JS representation
    • Scripts block the parser
      • Unless they're marked as async or defer
  • CSSOM from CSS
    • JS representation
    • Blocked by downloading CSS
  • Calculates the ???
    • Combines DOM and CSSOM
  • Calculate the render tree
    • Might be blocked by the resources you're downloading
  • Creates the a11y tree
  • Calculates layout from render tree
    • Flow, flexbox, grid
  • Paints the pixels
  • 89f233ea32dc5fba5edb096698d16c20.png
Last update: 2023-03-30