Depends on the printer make and model and the printer's LAN adapter.
On printers with an internal LAN adapter, you can usually find the IP
Address by either navigating through the printer's front panel menu or
printing a configuration/test page. Also, for internal LAN adapters, you
can usually change the IP address via the printer's front panel.
For external LAN adapters (so called "print server" devices), there's
usually a procedure for getting the device to send its current configuration
to an attached printer - consult the device's documentation (doesn't
necessarily work for all makes and models of attached printers). Setting
the IP address for these devices can often be done via Telnet - consult the
device's documentation.
For both internal and external LAN adapters, most support DHCP or BOOTP.
Most DHCP servers have a way to associate a fixed IP address with the
device's MAC (hardware) address (address reservations). If you are using
DHCP, you can assign a different IP address by changing the IP address
associated with the LAN adapter's MAC address. For external LAN adapters,
the MAC address is usually printed on a label somewhere on the device. For
internal LAN adapaters, print the configuration page or navigate through the
printer's front panel menus to get the LAN adapter's MAC address.
