Internet Fault Tolerance
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Practice Question
All three statements are TRUE. Statement I: Fault tolerance means the system continues functioning despite component failure - this network keeps working when a cable breaks, which is the definition of fault tolerance. Statement II: TCP/IP protocols include routing algorithms that discover alternate paths automatically when links fail - this is how the Internet handles router/cable failures globally. Statement III: Redundancy increases reliability (more paths = less likely to lose all connections) but also increases cost (more cables, routers, and maintenance). There's always a tradeoff between reliability and expense.
A) This misses Statement III. While redundancy DOES increase reliability, it also increases cost - you need extra cables, switches, and maintenance. Both reliability and cost increase. The AP exam often tests whether you understand tradeoffs, not just benefits.
B) This misses Statement II. TCP/IP's routing protocols (like OSPF, BGP) automatically discover and use alternate paths when links fail - this isn't magic, it's how the protocol is designed. The exam expects you to know that automatic rerouting is a fundamental Internet feature.
C) This misses Statement I, which is the most fundamental: redundant paths ARE fault tolerance. The whole point of having multiple paths is to tolerate faults. If you selected this, review the definition of fault tolerance - it means the system works despite failures.
Students sometimes think redundancy is "free" or forget it has costs. Every backup path requires physical cables, switches, power, and maintenance. The AP CSP exam emphasizes that engineering decisions involve TRADEOFFS - you gain reliability but pay more. Also, don't assume fault tolerance requires manual intervention - Internet protocols handle rerouting automatically.
For networking questions: (1) Fault tolerance = system works despite failures, (2) Redundancy = having backups (multiple paths, servers, power supplies), (3) TCP/IP handles rerouting automatically, not manually, (4) Reliability improvements usually increase cost. Look for answer choices acknowledging both benefits AND tradeoffs.