tailieunhanh - CompTIA SY0-201 Security+ Exam Guide phần 7

Chiều dài của chạy của sợi có thể được nhiều thời gian hơn, và dung lượng dữ liệu chất xơ cao hơn nhiều. Tuy nhiên, các kết nối đến một sợi là khó khăn và đắt tiền và chất xơ là không thể để mối nối. Kết nối chính xác vào cuối của một đường dây cáp quang là một công việc có tay nghề cao và | SY0 - 201 edged sword. It is cheaper when measured by bandwidth to use fiber than competing wired technologies. The length of runs of fiber can be much longer and the data capacity of fiber is much higher. But connections to a fiber are difficult and expensive and fiber is impossible to splice. Making the precise connection on the end of a fiber-optic line is a highly skilled job and is done by specially trained professionals who maintain a level of proficiency. Once the connector is fitted on the end several forms of connectors and blocks are used. Unguided Media Electromagnetic waves have been transmitted to convey signals literally since the inception of radio. Unguided media is a phrase used to cover all transmission media not guided by wire fiber or other constraints it includes radio frequency RF infrared IR and microwave methods. Unguided media have one attribute in common they are unguided and as such can travel to many machines simultaneously. Transmission patterns can be modulated by antennas but the target machine can be one of many in a reception zone. As such security principles are even more critical as they must assume that unauthorized users have access to the signal. Infrared Infrared IR is a band of electromagnetic energy just beyond the red end of the visible color spectrum. IR has been used in remote control devices for years and it cannot penetrate walls but instead bounces off them. IR made its debut in computer networking as a wireless method to connect to printers. Now that wireless keyboards wireless mice and PDAs exchange data via IR it seems to be everywhere. IR can also be used to connect devices in a network configuration but it is slow compared to other wireless technologies. It also suffers from not being able to penetrate solid objects so stack a few items in front of the transceiver and the signal is lost. RF Microwave The use of radio frequency RF waves to carry communication signals goes back to the beginning of the twentieth .

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