NAT drawbacks: Which items are recognized disadvantages of using NAT on a network edge device?

Introduction / Context:
NAT solves address depletion and eases provider changes, but it comes with trade-offs. Understanding these disadvantages helps architects decide when NAT is appropriate or when alternatives (IPv6, policy routing, or application gateways) are better.

Given Data / Assumptions:

• (1) Translation introduces switching path delays.
• (2) Conserves legally registered addresses.
• (3) Causes loss of end-to-end IP traceability.
• (4) Increases flexibility when connecting to the Internet.
• (5) Certain applications will not function with NAT enabled.
• (6) Reduces address overlap occurrence.

Concept / Approach:
True disadvantages: extra processing adds latency (1), NAT obscures original endpoints, hindering traceability and some security tools (3), and some protocols/applications break unless NAT-aware helpers or ALGs are used (5). Items (2), (4), and (6) are advantages, not drawbacks.

Step-by-Step Solution:

Verification / Alternative check:
Measure latency before/after NAT, review logs where original IPs are masked, and test protocols like SIP, H.323, or active FTP without ALGs.

Why Other Options Are Wrong:
3 and 4 / 2, 4 and 5 / 1 and 3: These sets either include advantages or omit a true disadvantage.

Common Pitfalls:
Relying on NAT as a security feature. While it obscures addresses, it is not a substitute for proper firewalling and inspection.

Final Answer:
1, 3 and 5