CyberCertPrepNetwork FundamentalsDNS & DHCPEASYFree question
Scenario
A DNS administrator notices that all DNS queries to the internal resolver for external domains (google.com, microsoft.com) are being answered within 2-5ms even on first query, while a fresh resolver in a lab takes 200-400ms for first queries.
What mechanism explains the production resolver's consistently fast response times for external domains?
- A.The production resolver has a direct peering connection to ICANN root servers
- B.The production resolver has cached query results (both positive answers and referrals) for popular domains from previous client queries; DNS caching within the TTL means subsequent queries for the same name are answered from the local cache without iterating through the root-TLD-authoritative resolver chain again, reducing response time from 200-400ms to single-digit milliseconds
- C.The production resolver is using HTTP/2 to batch multiple DNS queries in one connection
- D.The production resolver uses DNSSEC validation which pre-fetches all popular domain signatures
Why B is correct