From elsewhere...

[susandennis]

On Google+ (https://plus.google.com/110340962945642622580/posts/TuqJmCANjri), I said:

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So... if you reserve an ip address (static) for a device (say a laptop) on the router but do not 'assign' it on the device (the laptop properties allow as how it's using dhcp), have you actually done anything??

Comments

[mhaithaca.livejournal.com]

As far as the laptop knows, it's using DHCP, and on each connection to the router it will say "Oh look! I've got an IP address!" and not care what it is. As far as the router knows, the laptop will always have that particular address.

This is most helpful for situations where you need a particular device to be findable at a particular address on your home network. That's not the typical case for home laptop users.

It came in handy for me when I wanted a particular machine on my home network to respond as a web server, and another as a database server, though. In other words, they need predictable addresses, not random ones assigned each time they start up.