It often confusing to distinguish between an emulator and a simulator. Normally, an emulator is implemented in hardware, whereas a simulator is implemented in software. For example, a router emulator is used to test the performance or bugs in router hardware and software. The bugs may include clock timings, software instruction sequencing problems, and speed test. A simulator is implemented in software only. As a result, it will not have the ability to emulate the hardware environment such as clock timings, speed testing etc. Simulators are relatively slow since they are implemented in software. Emulation allows developers to see the real-time interactions between different hardware and software modules. It is also possible to connect real-world stimulus to peripherals and start debugging system behavior. Normally, a simulator is used during the initial stages of development, when the hardware is not yet ready. An emulator is more expensive as it is implemented in hardware and performs at the speed of real hardware or even better. A simulator is cost effective and the utility is limited to simulating software functional modules, often without the underlying hardware. The roles of a simulator and an emulator usually complement each other, thus providing a total testing environment.
The software offered by CertExams.com is a simulation software, completely based on software. No hardware is involved. It is felt that the performance degradation observed by using a simulator is very marginal and worth the cost advantage offered.