A Static IP address is a requirement if some hardware within your network act as a “server” or a “resource”.
Every devices (computers, tablets, smartphones) connected to a network has a unique address, known as IP address. The IP address has two components, the Network ID and the Host ID. Let’s look at the most common IP address schema on a home network, Class C, 192.168.1.8.

ip address

Class C IP address construction

The 16 bits Host ID allows for a maximum of 256 IDs (0 to 255) on the network. However, “0” and “255” are reserved and at least one ID is going to be used by the router, “1”. As a mini spoiler here, when assigning a static IP address, only the “Host ID” is affected.

Assigning IP address

Networked devices are getting their IP address by three methods, DHCP, Static DHCP and Static IP. The right terminology is IP lease. At the end of the lease, the IP can be renewed.

DHCP, Dynamic Host Configuration Protocol, is the most common way to assign IP addresses to hosts on the network. When a device connects to the network and it does not have an IP address, it broadcasts his information (Mac Address) over the LAN. Once it reaches the router (or a DHCP server), the router acknowledges the workstation by sending back its unique IP address along with other IP information (DNS server, gateway server, subnet mask).

The process is transparent to the user. As long as those workstations do not run any services, there is no need to know the IP address.

The drawback with DHCP, is the IP address can change upon reboot. That is an issue when running a server. If the IP address changes, the clients cannot make a connection until the new IP address is provided to the client.

Static DHCP or DHCP reservation.

As stated above, when a computer is on, it broadcasts its MAC Address over the network to find a DHCP server (or a router) to get an IP address. Instead of leasing the first available IP from the pool, the user can tie a MAC address (#1) to an IP address (#2). As long as the Mac Address does not change, the workstation will always be leased the same IP address.

static dhcp 1

Example of DCHP reservation

Although it can get the work done, it is not my preferred method. Dealing with MAC addresses can be a pain.

Static IP address

Assigning a static IP is basically doing the DHCP work. Instead of letting the DHCP randomly chose what IP to assign to a workstation, I can decide once and for all (unless I change my mind) what IP address a host would get on the network. Before I do, I would need to know what IP addresses are currently in used. I do not want two hosts with the same IP address.

How to get a list of currently used IP on a network.

The DOS command “arp -a” will return a list of IP address currently online, which means, it leaves out offline workstations.

“Advanced IP Scanner” provides a list of all the workstations.

Enter your network IP range to scan (#1), then click “Scan” (#2).

advanced ip scanner

Angry IP Scanner

How to assign Static IP address.

Once you have an idea of what values are available, We can go into the steps of actually assigning static IP addresses.

[Windows 7]: “Start” > “Control Panel” > “Network and Sharing Center” > “Local Area Connection” (#1)

lan nic

Click on “Properties” (#1).

On the next box, select “Internet Protocol Version 4 (TCP/IPv4)” (#2) and click “Properties” (#3).

nic settings

To manually setup and IP address requires five values, the Host IP address (#1), the Subnet mask” (#2), the “Default Gateway” (#3), the “Preferred DNS server”(#4) and the “Alternate DNS server” (#5, optional).

As an example, let’s say I’d like to set a static IP of 192.168.110.23 to a workstation. Based on my introduction, I know that the network ID is “192.168.110” and I want this PC to be assigned the “host ID” as “23”.

Here’s a tip, on a soho network, “Subnet mask”(#5) will always be “255.255.255.0”, the value for “Default Gateway” (#3) and “Preferred DNS Server”(#4) are the same as the router LAN IP address.

 static ip add

Best Practices:

Static IP
Plus: IP address does not change.
Minus: Keep track of IP address leases else there is a risk of an IP conflict.

DHCP:
Plus: IP maintenance free, don’t need to know, don’t care.
Minus: IP address may and can change, usually after a (soft or hard) reboot.

The best practice dealing with IP leases on a network is to use both. Use Static IP “server” type resource and DHCP for workstations. Separate the DHCP pool range, for instance, 2 to 100 are for DHCP leases and 101 to 254 are for the static IP pool.

dhcp pool

DHCP Pool. Since “1″ is already taken by the router, it was excluded from the pool.

Type of devices candidate for Static IP or DHCP

Static IPDHCP
* Computers running services: Web, FTP, RDP Access
* Networked (Wired/WiFi) Printer
* Webcam
* NAS
* Tablets
* Smartphones
* Laptops
* Chromebooks
* Desktop computers with no “services” installed

Conclusion

The tutorials focused on setting up a static IP on a Windows 7. The principle is the same regardless of the device or OS you are going to work with. Every device capable of connecting to a network has an area to configure its IP setting.

Heaven forbid if something goes wrong, simply go back to IP properties page and check “Obtain an IP automatically”, click “OK”. Verify that everything is back to normal and start over.

Filed in Computers. Read more about networking.

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