Networking
Explainer
DNS: Turning Names into IP Addresses
Typing umat.edu.gh can trigger queries to several servers before the page loads.
Quick check · tap an answer to continue
Lesson notes
Key points
- DNS, the Domain Name System, translates human-readable domain names into IP addresses that routers can use.
- The namespace is a hierarchy read right to left: root, then top-level domain like gh, then edu.gh, then umat.
- Your recursive resolver does the work, iteratively asking root, TLD and authoritative servers until it gets the answer.
- Answers are cached for their TTL, time to live, so repeat lookups skip the full chain and return quickly.
Definitions
- TTL
- Time to live: seconds a DNS record may be cached before it must be looked up again
Takeaway: DNS walks a name hierarchy from root down, then caches by TTL.
Quick check: Which server holds the final A record for umat.edu.gh?
- Authoritative server
- Root server
- DHCP server
DNSHierarchyRecursive resolverTTL caching
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