ITPEC FE Morning October 2018 Question 36
ITPEC FE Morning October 2018 — Question 36 of 80
NAPT (IP Masquerade) — allows multiple LAN devices to share a single global IP address.
Device A sits between the home LAN and the ONU (FTTH). One global IP is assigned to its WAN interface, while multiple PCs have private IPs behind it.
NAPT translates each private IP:port pair to the single global IP:unique port, enabling all PCs to access the Internet simultaneously.
Why not others:
- (a) DHCP — assigns IP addresses to devices, does not translate private to public
- (c) Packet filtering — filters traffic by rules (firewall function), unrelated to address translation
- (d) PPPoE — establishes a point-to-point session over Ethernet for ISP authentication, not address translation
Key rule: When multiple devices share one public IP → NAPT. When one device gets one public IP (1:1) → static NAT.
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