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Short note: Proxy load balancing

Short answer

Proxy load balancing spreads requests across a proxy array to avoid overload and improve availability. Methods include DNS round robin, hardware load balancer, hash-based CARP, redundant arrays, and ICP. Benefits are faster responses, higher hit ratio, scalability, fault tolerance, bandwidth savings, and easier maintenance.

Write a short note on Proxy load balancing.

Proxy load balancing means spreading client web requests across several proxy (cache) servers so that no single proxy is overloaded, while keeping response time low and service available if one fails. The proxies form a proxy array that appears to clients as one logical proxy.

Methods

  • DNS round robin: one name maps to many proxy IPs, used in turn. Simple, not load or failure aware.
  • Hardware / layer 4-7 switch: spreads connections by round robin or least connections and monitors the health of proxies.
  • Hash-based array (CARP): the URL hash picks one proxy, so each object is cached once and the total cache adds up.
  • Redundant array: objects are held in more than one proxy so a failure causes no cache loss.
  • ICP hierarchy: proxies query siblings before the origin.
 Clients --> [Load balancer / PAC] --> [P1][P2][P3] --> Internet

Benefits: faster responses, higher cache hit ratio, scalability (add proxies as demand grows), fault tolerance, less WAN bandwidth use, and easier maintenance.

Tools: Squid with CARP or cache peers, WCCP-capable routers, HAProxy.

✓ Answer checked by Claude Opus 5.5 (high effort)

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