Industrial campus: New client addresses cannot use the service
The incident
Engineering stations reach plant service gateways through the site core and two production aggregation layers. Client and service access branches each have their own transit router on either side of the regional hub. A client at .10 can use the primary service, but a client at .200 in the same subnet cannot. Both clients can reach the monitoring destination. Investigate plant gateway transport from R1: 10.178.0.0/24 to 10.178.8.0/24 (TCP/502), and 10.178.1.0/24 to 10.178.9.0/24 (TCP/4840).
Your objective
Restore both authorized service transports and return reachability, including clients and service hosts in both halves of the primary subnet. Keep R6 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R1 and R2. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.
The network
Link addressing (5)
- R1 R2
10.178.16.0/30 - R2 R3
10.178.17.0/30 - R3 R4
10.178.18.0/30 - R4 R5
10.178.19.0/30 - R3 R6
10.178.20.0/30
What you’ll practice
Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.