DNS Resolution & Caching
Software Engineer path · lesson 65 of 99Visualize the hierarchical Domain Name System and how local caching speeds up internet browsing.
DNS Resolution Process
Local Machine
DNS Hierarchy
Scroll right to see full DNS hierarchy
Resolve a domain from scratch
Order the lookups when nothing is cached yet.
Tap a piece, then tap where it goes — or drag it. Tap the tray to take one back.
- 1Drop a step here
- 2Drop a step here
- 3Drop a step here
- 4Drop a step here
- 5Drop a step here
- 6Drop a step here
Test your knowledge
If a DNS query is a "cache miss" at the OS level, where does the request typically go next?
The short version
DNS is the phonebook of the internet. Caching is like saving a number in your contacts so you don't have to look it up in the phonebook every time.
In more depth
Domain Name System (DNS)
DNS translates human-readable domain names (example.com) into machine-readable IP addresses (192.0.2.1).
The Hierarchy
Caching
To reduce latency and server load, DNS results are cached with a Time-To-Live (TTL) at the Browser, OS, and ISP resolver levels.
Interview Questions
References & Further Reading
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