In a Wireless LAN (WLAN), things are different. Its physical medium is the electromagnetic spectrum, which exists everywhere and respects few boundaries. Wi-Fi is now available at two different frequencies-IEEE 802.11b at 2.4GHz and IEEE 802.11a at 5GHz-and both can suffer interference from neighboring networks and other sources.. . .
In a Wireless LAN (WLAN), things are different. Its physical medium is the electromagnetic spectrum, which exists everywhere and respects few boundaries. Wi-Fi is now available at two different frequencies-IEEE 802.11b at 2.4GHz and IEEE 802.11a at 5GHz-and both can suffer interference from neighboring networks and other sources. The only way to know for sure which will work best in a particular environment is to perform a comprehensive site survey before buying a single access point.

Even if you have no intention of investing in Wi-Fi, knowing what's passing through your airwaves can still be useful. In addition to full-featured hardware and software analyzers, several vendors are pitching simpler, cheaper versions as security tools. These are designed to detect and track down rogue access points-WLAN base stations set up by employees without the IT department's knowledge. Almost all Wi-Fi hardware has its security features off by default, and the cheaper consumer-level models may not include any security at all, so these rogues can act as an open door into an otherwise well-protected network.

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