Technical interview guide

Load Balancing

Distributing traffic across multiple backend instances — algorithms, health checks, and layer 4 vs layer 7 balancing.

Read: 45 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: Network Engineer

Scope: Current HTTP/1.1, HTTP/2, QUIC, TLS 1.3, Forwarded, HAProxy 3.2, NGINX, Envoy, Kubernetes, AWS ELB, and Google Cloud Load Balancing references reviewed 2026-09-04.

Interview QA

Treat each question like a live interview question: answer out loud first (structure, assumptions, tradeoffs), then open the model answer to spot gaps and rehearse a tighter follow-up.

Curated: 2026-10-05 · Written: 2026-10-05 · Reviewed: 2026-10-03

QA-1

Choose Layer 4 or Layer 7 load balancing for a service.

QA-2

Select and validate a load-balancing algorithm.

QA-3

Balance multiplexed HTTP/2 upstream traffic.

QA-4

Use consistent hashing for a stateful cache or shard.

QA-5

Design layered backend health checks.

QA-6

Define readiness and liveness for a backend.

QA-7

Design zero-downtime load-balancer draining.

QA-8

Design retry policy across client, proxy, and service.

QA-9

How does TLS termination at a load balancer work, and what are the performance and security trade-offs of TLS offloading versus TLS bridging?

QA-10

Set a timeout hierarchy for an HTTP service.

QA-11

Design circuit breaking and load shedding.

QA-12

Set queue and admission policy for a proxy.

QA-13

Design TLS termination and upstream re-encryption.

QA-14

Preserve client address and scheme safely through proxies.

QA-15

Tune a load balancer's upstream connection pools.

QA-16

Decide whether to use session affinity.

QA-17

Calibrate heterogeneous backend weights.

QA-18

Coordinate load balancing with autoscaling.

QA-19

Design global traffic failover using DNS.

QA-20

Operate an anycast load-balanced service.

QA-21

Design health dependency isolation.

QA-22

Design overload behavior for a multi-tenant edge.

QA-23

Deploy a load-balancer configuration safely.

QA-24

Design load-balancer observability.

QA-25