hi, is there a way to find out a free IP address in LAN so that i can manually assign it to a network device ? Ping it is obviously essential but not enough. Thanks

"Ping it is obviously essential but not enough." Why not? If the machine doesn't respond to anything (and the configuration allows a response), the address is unallocated. Otherwise, you need access to wherever your network keeps this information. This is probably the router's routing table. I assume you are not using DHCP.

well, if you ping an IP address that is already assigned for a computer on the network, and that computer is currently offline, then you will not get a reply, right? when you assign this IP address to your new network device, when that computer goes online again, then you will get a conflict. I have run into this problem before. I'm using DHCP actually, so is there a potential problem if i assign the IP address manually? I believe not (but well, i can be wrong :)..I think if i use IP Address from 2-40 or 50 , not quite sure, these are for static IP address, above that range is for DHCP. Thanks for your reply.

"when you assign this IP address to your new network device, when that computer goes online again, then you will get a conflict." If the machine has a static address, you should know not to use it (plan ahead). If this is DHCP, you don't care. You take what is not taken (again, I assume the LAN in question is configured so a ping is allowed). If you have DHCP, don't assign anything manually. If you need them, keep a few addresses that are out of DHCP allocation range, and use these when you need too.

The real point is that, the Network administrator's job is to administrate the configuration of the network. And a big part of any administrators job is keeping and maintaining up to date accurate records. In this case, an accurate record of every device hooked to the network, its location, its MAC address and its assigned IP address if Static or if it is set for dynamic DHCP configuration. And what the DHCP address range is and how many devices might be online at any given time. There should be no need to "find" an available address as the network administrators records should show what the DHCP IP address range is, what range(s) are static, what every static IP address assigned is used for, and what addresses are not assigned. And no changes should be made to the Network configuration with out the Network Administrator verifying and recording each change. This applies, even if the "network" is just a personal home network with one system and a print server box, and the records are three lines of notes on sticky tab stuck to the router.