What it is: A Layer 4 load balancer for TCP/UDP traffic.

What it’s for:

• Very high performance, low latency.
• Stable IP addresses (useful for some clients).
• Non-HTTP protocols.

Key ideas:

• Works at connection level (TCP).
• Often used for high-throughput, real-time apps.

Exam cues:

• “TCP traffic, ultra low latency” → NLB.

Hard words:

• *layer 4* /ˈleɪər fɔːr/: tầng vận chuyển (TCP/UDP)
• *throughput* /ˈθruːpʊt/: thông lượng
• *stable* /ˈsteɪbəl/: ổn định