Industrial campus: The second client subnet gets no reply
The incident
Engineering stations reach plant service gateways through the site core and two production aggregation layers. Four routed metro nodes form a ring; the service gateway has a separate handoff. Requests reach both service networks, but the second client subnet cannot receive replies. The first client subnet still works. Investigate plant gateway transport from R2: 10.176.130.0/24 to 10.176.136.0/24 (TCP/502), and 10.176.131.0/24 to 10.176.137.0/24 (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 R3 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R2 and R1. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.
The network
Link addressing (5)
- R1 R2
10.176.144.0/30 - R2 R3
10.176.145.0/30 - R3 R4
10.176.146.0/30 - R4 R1
10.176.147.0/30 - R4 R5
10.176.148.0/30
What you’ll practice
Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.