mod_proxy vs. mod_jkSo what to use when? It depends on your topology. In case you already have or need Apache 2.2 functionality you have the choice to choose between mod_proxy and mod_jk. Mod_jk works very well on Apache 2.2, so it all depends on the functionality needed: mod_proxy
- No need for a separate module compilation and maintenance. mod_proxy, mod_proxy_http, mod_proxy_ajp and mod_proxy_balancer comes as part of standard Apache 2.2+ distribution
- Ability to use http https or AJP protocols, even within the same balancer.
- mod_proxy_ajp does not support large 8K+ packet sizes.
- Basic load balancer
- Does not support Domain model clustering
- Advanced load balancer
- Advanced node failure detection
- Support for large AJP packet sizes
- Need to build and maintain a separate module
출처 : https://community.jboss.org/people/mladen.turk/blog/2007/07/16/comparing-modproxy-and-modjk