He saved the Packet Tracer file— Leone_Final_OSPF_Fixed.pkt —and uploaded it with two minutes to spare. As he shut his laptop, he looked at the topology one last time. The little green triangles next to each router link now glowed solid, and the packets flowed between Chicago, Dallas, Atlanta, and Seattle like digital blood through a revived body.
A cheer erupted from Leo’s throat, startling a janitor who was mopping the hallway outside. It was just a simulation. Just virtual routers on a virtual network built by a virtual software company. But the feeling was real. The puzzle had been solved. The pieces had clicked.
R4#show ip ospf neighbor
It was the capstone of CNT-210, and Professor Voss had designed it with the precision of a medieval torturer. Four routers—R1 in Chicago, R2 in Dallas, R3 in Atlanta, R4 in Seattle. Each one was misconfigured in a unique, maddening way. R1 had a passive-interface set wrong. R2 was advertising a route to a network that didn't exist. R3 had an OSPF cost of 1 on a T1 line, creating a routing loop the size of Texas. And R4… R4 just refused to speak to anyone.
The clock on the wall of Lab 3B read 11:47 PM. Thirteen minutes to save his grade. Leo’s eyes, dry and aching, darted between the glowing topology on his screen and the cryptic lines of his lab instructions. cisco packet tracer exercises
The screen flickered. Then, a miracle:
R4(config-router)#network 10.0.4.0 0.0.0.255 area 0 He saved the Packet Tracer file— Leone_Final_OSPF_Fixed
Nothing. Dead silence. The virtual equivalent of a dial tone in an empty house.
"Final Exercise: The Four-Site OSPF Nightmare." A cheer erupted from Leo’s throat, startling a
R4#show ip ospf neighbor
A small victory: the command took. But still, no hello packets. No DR election. Just a cold, digital void.