Which DNS strategy primarily provides automatic failover between a pair of servers?

Which DNS strategy primarily provides automatic failover between a pair of servers?

• A. Anycast routing to nearest server
• B. Primary/secondary DNS failover
• C. DNSSEC improvement
• D. CNAME aliasing

Answer: (B)

Automatic failover between two servers is achieved with a primary/secondary DNS failover approach. One DNS server is the primary authoritative source for the domain’s records, while a secondary server holds a synchronized copy to take over if the primary fails. Under normal operation, clients resolve to the primary’s IP. Health checks monitor availability, and when the primary goes down, the failover mechanism updates DNS so queries start resolving to the secondary, keeping services reachable. The speed of this switch depends on the DNS records’ TTL: shorter TTLs allow faster failover but increase DNS query load. This method specifically targets automatic failover between two servers, and differs from anycast routing (which sends requests to the nearest node based on network topology), DNSSEC (which protects DNS data integrity), and CNAME aliasing (which maps one name to another without providing failover by itself).

Automatic failover between two servers is achieved with a primary/secondary DNS failover approach. One DNS server is the primary authoritative source for the domain’s records, while a secondary server holds a synchronized copy to take over if the primary fails. Under normal operation, clients resolve to the primary’s IP. Health checks monitor availability, and when the primary goes down, the failover mechanism updates DNS so queries start resolving to the secondary, keeping services reachable. The speed of this switch depends on the DNS records’ TTL: shorter TTLs allow faster failover but increase DNS query load. This method specifically targets automatic failover between two servers, and differs from anycast routing (which sends requests to the nearest node based on network topology), DNSSEC (which protects DNS data integrity), and CNAME aliasing (which maps one name to another without providing failover by itself).