Consider an enterprise network with two Ethernet segments, a web server and a firewall, connected via three routers as shown below. [Enterprise network diagram: Two Ethernet segments (left side), a Web Server and a Firewall (right side), interconnected through three routers. Each router interface connecting a distinct segment forms a separate subnet.] What is the number of subnets inside the enterprise network? A. 3 B. 12 C. 6 D. 8

GATE 2022 · Computer Networks · Ethernet · medium

Answer: 6 subnets (option C).

  1. Identify LAN segments: Two Ethernet segments are present on the left side of the network, each forming one subnet. Count = 2.
  2. Count inter-router links: Three routers form two point-to-point links: R1-R2 and R2-R3. Each link is a separate subnet. Count += 2 = 4.
  3. Count server and firewall subnets: The web server and the firewall are each on their own subnet connected to router R3's interfaces. Count += 2 = 6.
  4. Total subnet count: 2 (Ethernet LANs) + 2 (inter-router links) + 2 (web server + firewall) = 6 subnets.