AKS ISSUE
│
├── 1. Is the app unreachable?
│   │
│   ├── External access issue
│   │   ├── Check DNS
│   │   ├── Check Public/Internal Load Balancer
│   │   ├── Check Ingress Controller
│   │   ├── Check Service
│   │   └── Check Pods
│   │
│   └── Internal access issue
│       ├── Check Service name
│       ├── Check CoreDNS
│       ├── Check Network Policy
│       └── Check Pod-to-Pod connectivity
│
├── 2. Are pods not running?
│   │
│   ├── Pending
│   │   ├── Not enough CPU/memory
│   │   ├── Taints/tolerations issue
│   │   ├── Node selector/affinity issue
│   │   ├── Cluster autoscaler maxed out
│   │   └── Subnet IP exhaustion
│   │
│   ├── ImagePullBackOff
│   │   ├── Wrong image name/tag
│   │   ├── ACR permission missing
│   │   └── Network/DNS issue to registry
│   │
│   └── CrashLoopBackOff
│       ├── App bug
│       ├── Missing secret/config map
│       ├── Bad env variable
│       └── Probe misconfigured
│
├── 3. Are nodes unhealthy?
│   │
│   ├── Node NotReady
│   │   ├── VMSS health
│   │   ├── Kubelet issue
│   │   ├── Disk pressure
│   │   ├── Memory pressure
│   │   └── Network issue
│   │
│   └── Node pool issue
│       ├── Upgrade failed
│       ├── Scale operation failed
│       └── Quota/capacity issue
│
├── 4. Is it a networking issue?
│   │
│   ├── DNS failure
│   │   ├── CoreDNS
│   │   ├── Private DNS zone
│   │   └── Custom DNS forwarders
│   │
│   ├── Routing failure
│   │   ├── UDR
│   │   ├── Azure Firewall
│   │   ├── NSG
│   │   └── Route table association
│   │
│   └── Private Endpoint failure
│       ├── DNS resolves to private IP?
│       ├── VNet peering working?
│       ├── NSG allows traffic?
│       └── Private endpoint approved?
│
├── 5. Is it identity/security?
│   │
│   ├── Azure resource access failing
│   │   ├── Managed identity assigned?
│   │   ├── RBAC role correct?
│   │   └── Workload Identity configured?
│   │
│   └── Kubernetes access failing
│       ├── Azure AD login?
│       ├── Kubernetes RBAC?
│       └── Namespace permissions?
│
└── 6. Is it platform-wide?
    │
    ├── Multiple services affected
    │   ├── Check Azure Service Health
    │   ├── Check regional outage
    │   └── Check dependency outage
    │
    └── Only one app affected
        ├── Check recent deployment
        ├── Rollback if needed
        └── Compare config/secrets

DNS → LB/Ingress → Service → Pod → Node → Network → Identity → Azure