TechKnowSurge
CompTIA Network+ 3.4 Cisco CCNA 4.3
TechKnowSurge Catalog Interactives Predict DNS Caching and TTL
InteractiveNetworkFree

Predict DNS Caching and TTL

A site moved, but the old address is cached: predict what DNS caching and the TTL do.

⚑ Complete this interactive to capture a CTF flag worth 5 points.

About this interactive

From the lesson: - **Caching:** the authoritative answer is stored, so later requests use the cached copy instead of asking the root, TLD and domain servers again. - **TTL:** the countdown stored with the cached record. Until it runs out, the old answer stays in use, even if the record has changed. - **Planning a change:** with a 10-day TTL, clients may keep an old address for 10 days. Lower the TTL to a few minutes well before the move (at least one old TTL ahead), make the change, then raise it again. - **The cost of short TTLs:** more lookups, which mattered more when bandwidth was scarce and still matters on slow links. - **Caching servers:** an ISP's caching server answers popular names for all its customers, and a company DNS server caches for everyone in the LAN, so fewer lookups leave the network and the root servers are spared.

What you'll learn

Aligned to

CompTIA Network+
3.4 Given a scenario, implement IPv4 and IPv6 network services.
Cisco CCNA
4.3 Explain the role of DHCP and DNS within the network

Key terms

DNS Caching
The local storage of DNS query results so that future requests for the same domain can be resolved without repeating the full lookup process.
Caching Server
A server that stores copies of DNS query results to serve repeated requests from multiple clients without forwarding each query to authoritative DNS servers.
Authoritative Name Server
A DNS server that holds the definitive DNS records for a specific domain and provides the final IP address answer to a resolution query.
Domain Name System
DNS
A hierarchical naming system that translates human-readable domain names into IP addresses.
Root Server
A DNS server at the top of the DNS hierarchy that responds to queries by directing resolvers to the appropriate top-level domain server.

Topics

Dns Dns Caching Ttl Caching Server Interactive Predict

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →