The journey of a web request
What happens between typing an address and seeing the page: DNS, the TCP connection, TLS encryption, the HTTP request and response, rendering. Each step through its definition, real situations and what breaks when it fails.
- 42 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- The steps
- The connection
- The response and the page
A few cards from the deck
URL: what is it?
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The address of a resource: the protocol (https), the domain name and the path
The browser reads from it the name to resolve, the port to use (443 by default for https) and what to ask the server for.
In what order do the steps happen to show https://exemple.fr on a first visit?
- TCP, then DNS, then TLS, then HTTP
- DNS, then TLS, then TCP, then HTTP
- DNS, then TCP, then TLS, then HTTP
- HTTP, then DNS, then TCP, then TLS
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DNS, then TCP, then TLS, then HTTP
You need the IP address (DNS) to open a connection (TCP), a connection to encrypt it (TLS), and an encrypted channel to send the request (HTTP).
DNS resolution: what is it?
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Turning a domain name into an IP address
Machines reach each other by IP address: without one, no connection can be made.
On a new connection, how many round trips are needed before sending the HTTP request over HTTPS with TLS 1.3, not counting DNS?
- 0
- 1: TLS happens without TCP
- 2: one for TCP, one for TLS
- 4
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2: one for TCP, one for TLS
TCP takes one round trip, then TLS 1.3 another: that is why reusing a connection saves time.