The Apache "KeepAlive" directive should be configured appropriately.
(1) On / Off
(1) Apache configuration file: KeepAlive directive
L1 10. Denial of Service (DoS) Protective General Directives pg 16
1.13 Denial of Service Prevention Tuning p21
CIS Apache Benchmark for Unix v1.7 For Apache Versions 1.3 and 2.0
CIS
2007-07-01
Version 1.7
Prose (PDF)
Security Configuration Benchmark For Apache Web Server
CIS
2008-11-01
Version 2.2.0
Prose (PDF)