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Knowing What's On Your LAN

Whenever you are diagnosing a network problem, whether it involves simple Windows Networking connectivity, or file sharing, you can run native Windows commands like "net view". This tells you what servers can be seen on the LAN.

Unfortunately, "net view" is an application level diagnostic, and requires Server Message Blocks aka SMBs. Lack of SMBs, frequently caused by a misconfigured or overlooked personal firewall, is a common symptom. When you're diagnosing a network problem, you have to start at the lower levels, and work upwards. What about some diagnostics at a lower level, just to verify IP connectivity?

For an immediate scan of the subnet, I rely upon three free products:

Each tool will start with the subnet that your computer is attached to, and scan each possible IP address on that subnet. For each IP address responding, you can find out host name, MAC address, and response time. This is a good start, for finding, and tracking, computers on your network.

Remember, though, both of these products list hosts using Internet Protocol. If your LAN uses alternate transports like IPX/SPX or NetBEUI, neither will be very useful.

If you need to associate a MAC address with its vendor, the IEEE OUI / Company_id Assignments database can be searched for this information.

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