last dump ccna 200-125

last dump ccna 200-125.9. which coding method is used for DSSS binary phase shift keying at IMbit/s data rate?a. 11-chip Barker code b. 8-chip CCK c. 11-chip CCK d. 8-chip Barker code10. Which of the following occurs when a portable computer using Dynamic RateShifting (DRS) and operating at an access rate of llMbit/s moves away from an Access Point (AP, AccessPoint)?a. this computer roams to another AP b. this computer loses connectivity c. this rate dynamically shifts to 5.5Mbit/s d. this rate increases, providing higher throughput1.2 Basic Topics1.2.1 Wireless LANs Although wireless networks only began to enter the market in the 1990s, the technology had actually been around since the 19th century. The musician and astronomer William Herschel (1738^1822) discovered infraredlight, a light invisible to the human eye. The discovery of infrared light pointed the way to the theory of electromagnetic waves, which was studied in depth by James Maxwell (1831.1879). Most of his discoveries about electromagnetism were based on the work of Mickael Faraday (1791^ 1867) and Andre-Marie Ampere (1775 - 1836), researchers who preceded James Maxwell in this field. Heinrich Hertz (1857.1894) built on Maxwell's discoveries by demonstrating that electromagnetic waves travel at the speed of light and that electric currents can travel over these electromagnetic waves. As interesting as these discoveries are, you may not yet understand how they relate to wireless local area networks ( WLANs). The relationship is that in a standard LAN, data is transmitted as electrical signals over wires such as Ethernet cables. Hertz's discoveries opened up an over-the-air channel for data transmission, with the signal still being electrical, but without the need for wires. Thus, WLAN with its premise1.2 Basic Themes 5The relationship between WLAN and the other discoveries made in the previous section is simply this: WLAN is a local area network that transmits data between devices without the need for cables, and this technology emerged from the discoveries and research done by Herschel, Maxwell,Ampere and Hertz. WLAN is implemented by means of Radio Frequency (RF, RadioFrequencies).The purpose of using RF is to send as much data as possible as far and as fast as possible. The problem is that for RF there are many aspects that need to be overcome or dealt with. One of these issues is interference, which is discussed in detail in Chapter 5. it is now sufficient to understand the concept of WLAN, but this is not necessarily an easy task. Before understanding what problems can occur and how to overcome them, it is important to first understand how RF works.1.2.2 How to Obtain Bandwidth from RF Signals