January 24th, 2013, 12:40 AM
Join Date: Jul 2012
Thanked 556 Times in 440 Posts
For a variety of reasons I assign static IP addresses to most of the hosts on my home network. What I've learned to do is set my "router" (I hate that term since nobody uses them for routing) to offer DHCP leases for less than the entire subnet.
Most home and "small business" Internet gateway "routers" are preset to use one of the 192.168.*.* non-routable subnets, which gives a total of 254 available IP addresses. What I do is reserve the first half, from 192.168.*.2 to 192.168.*.127, and a few IP addresses near the end (192.168.*.251-192.168.*.254) for static IP. I do this by setting the DHCP server range from 192.168.*.128 to 192.168.*.250.
For as long as I can remember, it's been traditional to reserve a block of IP addresses at the beginning and end of a subnet for routers, bridges or other networking equipment. You'll see why as you learn more about good practices in large managed networks. For now you can trust that it's a Good Thing.
Another tradition has been to put the servers down low in the range of IP addresses. The biggest benefit of doing it this way is that old-timers are likely to have long-standing networks arranged this way, and it makes it easy to guess the IP address of a host that you can't find by name when there's a problem with DNS and/or WINS.
Here's an example of how my home network is arranged:
What's up with the two gateways? A well-designed business network will have one or more alternate paths to the Internet. If one path fails, the router(s) for the alternate path(s) assume the default gateway address automatically (if they're configured that way). Since you're learning the business way, you should be prepared for stuff like that.
I reserve easy to remember IP blocks for various host types:
192.168.0.10 is my printer. (In the workplace, many printers are Ethernet connected.)
192.168.1.11-19 is reserved for servers (file, print etc.)
192.168.1.21-29 is reserved for desktops.
192.168.1.31-39 is reserved for virtual machines running on the desktops.
192.168.1.41-49 is for more VMs...and so on.
192.168.1.91-99 is reserved for my TV, TiVos and other media devices.
192.168.1.128-250 are DHCP-assigned addresses that is used by new machines before I've configured a static IP address for them, and for my wirelessly connected devices.
192.168.1.251-254 is reserved by tradition. My Slingboxes take these addresses without asking, so it was good that I reserved that space!
The above is only an example. You can assign static IP addresses and DHCP ranges that suit you. When you set up a local DNS server, you'll probably find times when it's really helpful to know (more or less) the IP address of a host when you can't reach it by name. Being able to ping an address, or a small number of IP addresses to verify that a host is up saves time.
I've seen some Internet gateway "routers" that allow you to use DHCP to assign fixed IP addresses using DHCP. This is not the same as configuring a true static IP address! For your purposes you'll want to have an IP block that doesn't get DHCP assignments, and therefore can be used to configure your machines with a static IP address on.