Which statement describes the relationship of SPI firewalls in terms of safety and cost?

• A. They are expensive and unsafe
• B. They balance high safety with low cost
• C. They are low safety and cheap
• D. They are not used in border networks

Answer: (B)

Stateful Packet Inspection firewalls provide a solid balance of protection and cost. By tracking the state of active connections, they enforce rules based on the context of traffic, making it much harder for spoofed or invalid packets to slip through and allowing only legitimate, established conversations. This gives higher safety than simple, stateless filtering while keeping implementation costs reasonable, especially compared with more expensive inspection techniques. In border networks, where you need reliable security without excessive expenditure, this balance is ideal: strong protection that isn’t prohibitively costly. The other statements imply either excessive cost or weak protection or claim these firewalls aren’t used at borders, which isn’t accurate.