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Networking Case Studies

20 incident case studies for hands-on troubleshooting practice.

Case Study Description
Arp Flux Duplicate Ip ARP Flux / Duplicate IP
Asymmetric Routing One Direction Asymmetric Routing / One-Direction Failure
Bgp Peer Flapping BGP Peer Flapping
Dhcp Relay Broken DHCP Not Working on Remote VLAN
Dns Resolution Slow DNS Resolution Taking 5+ Seconds Intermittently
Dns Split Horizon Confusion DNS Split-Horizon Confusion
Duplex Mismatch Symptoms Duplex Mismatch
Firewall Shadow Rule Firewall Shadow Rule
Jumbo Frames Partial Jumbo Frames Enabled But Some Paths Failing
Lacp Mismatch One Link Hot LACP Mismatch / One Link Hot
Mtu Blackhole Tls Stalls MTU Black Hole / TLS Stalls
Multicast Not Crossing Router Multicast Traffic Not Crossing Router
Nat Exhaustion Intermittent NAT Port Exhaustion / Intermittent Failures
Network Loop Broadcast Storm Network Experiencing Broadcast Storm and High CPU on Switches
Ospf Stuck In Exstart OSPF Adjacency Stuck in ExStart/Exchange State
Proxy Arp Causing Issues Proxy ARP Causing Unexpected Routing Behavior
Source Routing Policy Miss Traffic From Specific Source Not Taking Expected Path
Ssl Cert Chain Incomplete TLS Works From Some Clients But Fails From Others
Tcp Rst After Idle TCP Connections Reset After Idle Period
Vlan Trunk Mistag VLAN Trunk Mistag