The objective of this paper is to report findings from simulating and testing local area network (LAN) connectivity using Windows XP operating system and Cisco Networking Academy network devices. In this study, a simple routing protocol, RIP, is used as routing protocol. Two different techniques, Cisco Networking Academy hardware lab and Cisco Packet Tracer 4, were used to compare their performance to simulate network connectivity. Primary findings showed that the settings of the Windows XP firewall on the host computer have a direct impact on the test results. These findings are critical as there are no similar reports in the literature and only a careful investigation allowed the researchers to come to this conclusion. Furthermore, study results also offer suggestions for fixing problems that hinder simulation results of LANs that use Windows XP workstations. These findings can help CCNA students and faculty understand the reasons for unexplained connectivity problems when performing CCNA labs. The study also provides a simple method to avoid connectivity problems when using Windows ping.exe and tracert.exe which implement the TCP/IP protocol ICMP