Data center: Neighbor recovery is only the first repair
The incident
Application workers connect to database and connection-pool subnets through separate access and service aggregation layers. Every core router peers with the other three, between separate client and service handoffs. Both service networks are unreachable after a configuration rollout. Restoring the service-edge neighbor alone does not restore every required flow. Investigate database connectivity from R1: 10.167.64.0/24 to 10.167.74.0/24 (TCP/5432), and 10.167.65.0/24 to 10.167.75.0/24 (TCP/6432).
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 R1 and R4. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.
The network
Link addressing (8)
- R1 R2
10.167.80.0/30 - R2 R3
10.167.81.0/30 - R2 R4
10.167.82.0/30 - R2 R5
10.167.83.0/30 - R3 R4
10.167.84.0/30 - R3 R5
10.167.85.0/30 - R4 R5
10.167.86.0/30 - R5 R6
10.167.87.0/30
What you’ll practice
Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.