what OS are you using? windows XP pro allows this by going into network settings, then right click the network connection, go to properties. when in properties find your “Internet Protocol TCP/IP” protocol and click properties. in the properties section set the GENERAL tab section to obtain IP address automatically and it will get it’s address from DHCP. then in the ALTERNATE CONFIGURATION tab you can enter a static IP address. this should work for two different networks, (or more as long as you only need one with static IP), and is exactly why it was developed.
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Here is what I recommend:
Don’t use static’s at the office. If you already have a DHCP server running do DHCP Reservations by Mac-Address. That way the laptops always get the same address everytime they connect and they don’t have to do any config to their laptop ever. And you could do a reservation for both their wireless card and ethernet card. If you need specific help with the config of the DHCP server…let me know.
I’d recommend adding another DHCP scope which has just enough IPs to account for all the machines which have reservations. When another machine is added increase the size of the range one IP larger.
You can learn a little code and make a couple small batch files, one you would click when home that changes your ip address to dhcp and runs a release renew.. One you would click on to change it back to static and set the ip address for you.
One way to do it: http://forums.devshed.com/networking-help-109/netsh-command-usage-in-a-batch-file-to-set-ip-130387.html