Backup network: Hardening interrupts service reachability
The incident
Backup agents traverse a routed storage boundary while replication monitoring and a lab tenant share a separate branch. Three two-hop regional branches meet at one interchange, separating client, service and partner traffic. Service reachability disappeared after an OSPF hardening change. Interface addressing is unchanged and the service uplink still responds locally. Investigate backup transport from R1: 10.174.128.0/24 to 10.174.136.0/24 (TCP/2049), and 10.174.129.0/24 to 10.174.137.0/24 (UDP/111).
Your objective
Restore both authorized service transports and return reachability, including clients and service hosts in both halves of the primary subnet. Keep R7 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R1 and R6. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.
The network
Link addressing (6)
- R1 R2
10.174.144.0/30 - R2 R3
10.174.145.0/30 - R3 R4
10.174.146.0/30 - R4 R5
10.174.147.0/30 - R3 R6
10.174.148.0/30 - R6 R7
10.174.149.0/30
What you’ll practice
Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.