Define Availability.

• A. The likelihood that the network is available when its use is required
• B. The physical arrangement of cables
• C. The maximum data rate of a link
• D. The cost to maintain service

Answer: (A)

Availability measures how often the network is up and usable when you need to use it. It’s about uptime—the portion of time the service is accessible. In practice, it’s expressed as a percentage of time the network is available, and it can be related to MTBF and MTTR with the formula MTBF / (MTBF + MTTR). Higher availability means less downtime, often achieved through redundancy, reliable failover, and proactive maintenance. The other options describe topology (how cables are arranged), capacity (maximum data rate), or cost, which are different concepts than being accessible when required.