In this chapter I compare the RTT measurement differences between ping and tcpdump, and between pairs of tcpdump. I first introduce in Section 4.1 the design of an experiment that has helped determine the best measurement configuration in the study. Based on this experiment, I compare in Section 4.2 ping's RTT measurement with tcpdump's RTT measurement, and in Section 4.3 pairs of tcpdump measurements. In Section 4.4 tcpdump measurements of two dedicated monitoring machines are compared. Here a dedicated machine is defined as one that runs tcpdump in single-user mode, without being NTP configured, and with the Random Access Memory (RAM) disk configured as the output media for the measurement data. In Section 4.5 the measurement difference between running ping in multi-user mode and single-user mode is compared. Finally, based on the findings in these sections, I make conclusions in Section 4.6.