HomeIncident briefing
Back to the library
INCIDENT #001 · ROUTING

The unreachable branch

Easy8 minutesFree lab

The incident

The Albany branch team reports that clients in 10.41.10.0/24 cannot use the service at 10.41.30.10 after last night's configuration change. Directly connected transit addresses still respond. You are the engineer on call. Investigate the path, identify the cause, and restore service.

Your objective

Restore service between 10.41.10.1 and 10.41.30.10, including the return path. Preserve the physical topology and transit connectivity.

The network

Network topology3 devices 2 links

The unreachable branch — network topologyR1: Client edge. R2: Transit core. R3: Service edge. R1 connects to R2. R2 connects to R3. Connections show physical links, not service health.R1 ↔ R2 · 10.41.12.0/30R2 ↔ R3 · 10.41.23.0/30R1Client edgeR1 · Client edge · Starting deviceR2Transit coreR2 · Transit coreR3Service edgeR3 · Service edge
Physical links · Service health not shown
Link addressing (2)
  • R1 R210.41.12.0/30
  • R2 R310.41.23.0/30
3 devices · Cisco IOS syntax · Simulated network

What you’ll practice

static routingroute lookup

Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.