Cisco Certified Support Technician (CCST) NetworkingIP ServicesHard
A large enterprise network uses a distributed architecture with multiple internal DNS servers. Users in one branch office are reporting issues resolving hostnames for servers located in another branch office, while external websites are resolving correctly. The network administrator suspects a problem with how DNS queries are forwarded or resolved internally. Which DNS server role is responsible for forwarding queries to other DNS servers when it cannot resolve a name locally?
- AForwarding DNS Server
- BAuthoritative DNS Server
- CCaching-Only DNS Server
- DRecursive DNS Server
Show answer & explanationAnswer & explanation
Correct answer: A. Forwarding DNS Server
A forwarding DNS server (often configured as a recursive server) is specifically configured to send queries that it cannot resolve locally to another designated DNS server (the 'forwarder'). This is commonly used in enterprise networks to centralize external lookups or to handle queries for specific internal zones.
Why the other options are wrong
- B. An authoritative DNS server holds the master records for a specific domain.
- C. A caching-only DNS server stores resolved queries but does not host zones itself.
- D. A recursive DNS server performs the full query process on behalf of the client, but a 'forwarding' server specifically sends those queries to another server.
DNS Forwarding Server
A forwarding DNS server is configured to send all DNS queries that it cannot resolve from its local cache or authoritative zones to a specific upstream DNS server, known as a forwarder. This is common in enterprise networks for security, performance, and management.
- Sends unresolved queries to a designated upstream server.
- Can improve security by limiting direct external communication.
- Can improve performance by centralizing external lookups.
- Often used in conjunction with recursive functionality.
Memory trick: Forward means sending it on to someone else.