A central mapping computer (for DNS-like service) presents a reliability issue. Which statement correctly identifies a reliability flaw?

A central mapping computer (for DNS-like service) presents a reliability issue. Which statement correctly identifies a reliability flaw?

• A. If that computer turns off, domain name mappings become unavailable.
• B. It would automatically scale to handle any amount of requests.
• C. It eliminates the need for other DNS servers.
• D. It prevents any security vulnerabilities.

Answer: (A)

A reliable DNS-like service depends on availability across multiple systems, not just one. A central mapping computer creates a single point of failure: if that machine turns off or cannot be reached, domain name lookups fail and users can’t reach services. This is exactly what reliability aims to prevent, so spreading the mapping responsibility across redundant servers, with replication and automatic failover, makes the service much more resilient. In practice, DNS uses multiple authoritative servers and network routing to keep mappings available even when some parts of the system fail. The other statements don’t describe a reliability flaw: automatic scaling helps availability, you still need other DNS servers for redundancy, and no system can claim to prevent all security vulnerabilities.

A reliable DNS-like service depends on availability across multiple systems, not just one. A central mapping computer creates a single point of failure: if that machine turns off or cannot be reached, domain name lookups fail and users can’t reach services. This is exactly what reliability aims to prevent, so spreading the mapping responsibility across redundant servers, with replication and automatic failover, makes the service much more resilient. In practice, DNS uses multiple authoritative servers and network routing to keep mappings available even when some parts of the system fail. The other statements don’t describe a reliability flaw: automatic scaling helps availability, you still need other DNS servers for redundancy, and no system can claim to prevent all security vulnerabilities.