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4.1.2. Load Balancing Rules
Components:
Load Distribution Modes:
| Mode | Hash | Use Case |
|---|---|---|
| Default (5-tuple) | Source IP, port, dest IP, port, protocol | Stateless apps |
| Source IP (2-tuple) | Source IP, dest IP | Session affinity |
| Source IP + protocol (3-tuple) | Source IP, dest IP, protocol | Same-client affinity |
Health Probes:
| Protocol | Best For |
|---|---|
| TCP | Simple availability check |
| HTTP/HTTPS | Application-level health (checks specific path) |
Probe settings:
- Interval: How often to probe (seconds)
- Unhealthy threshold: Failed probes before marking unhealthy
Outbound Rules (SNAT):
Standard Load Balancer provides explicit outbound SNAT configuration:
| Setting | Purpose |
|---|---|
| Frontend IP | Source IP for outbound |
| Backend pool | VMs using this rule |
| Protocol | TCP, UDP, or both |
| Allocated ports | SNAT ports per instance |
| Idle timeout | How long to keep connections |
⚠️ Exam Trap: Without explicit outbound rules or NAT Gateway, Standard LB backends have NO outbound internet access. This is by design (secure by default).
Written byAlvin Varughese
Founder•15 professional certifications