World of Computer Networking Your CCNA start - Domain Name System (DNS) Query Resolution Caching Process

The video tutorial explains the process of DNS resolution and the importance of caching in optimizing DNS performance. It covers different levels of caching, including web browser, operating system, and DNS recursive resolver caches. The tutorial emphasizes the significance of cache time-to-live (TTL) to ensure data accuracy and prevent connectivity issues. It concludes with a brief mention of DNS round robin responses.

Why is caching important in DNS resolution?

• To increase the load on root name servers

• To avoid using authoritative name servers

• To delay every DNS request

• To reduce delays and server load

Which cache is used first when a web browser repeats a DNS query?

• DNS recursive resolver cache

• Root name server cache

• Web browser cache

• Operating system cache

What happens if a DNS resolver has an S record cached for a domain?

• It queries the root name server

• It queries the TLD name server

• It sends a request to the web browser cache

• It directly queries the authoritative name server

Why must DNS cache have a specific time to live?

• To prevent any DNS updates

• To allow DNS records to change frequently

• To keep data up-to-date and accurate

• To ensure data remains obsolete

How long did DNS record updates take several years ago?

• A few days

• Up to 24 hours

• Several minutes

• A few seconds