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Advanced Networking Options – Static IP Address

Many of POSIM services communicate over your local area network (LAN) using their IP Address. For best results, you should set up any server functioning device with a static IP address. These devices include:

  • POSIM / PayStream Server Computer
  • Each Payment Terminal Device
  • Networked Printers

A static IP address will ensure that the device always keeps the same IP address even if the network or device is restarted. Continue reading below to learn more about the terminology building up to an understanding of a LAN device static IP address.

What is an IP address?

Each device connected to your network is assigned an IP, or Internet Protocol, address. This is comparable to the physical street address of a home. An internal IP address typically has the form of,, or There are basically 4 groups of up to 3 numbers separated by a dot: This address is used by the router and other network devices to communicate. The router keeps track of each address so it knows where to pass information over the network. Typically a router is setup with a DHCP server that will assign IP addresses as devices are connected.

What is a DHCP server?

A DHCP, or Dynamic Host Configuration Protocol, the server is used to assign IP addresses to network devices. Most, if not all, home or small business level routers come with a DHCP server built in. Typically the DHCP server is setup with a range of IP addresses to assign. For example, the range could be from to This would accommodate for 99 addresses being assigned. As devices come and go on the network, the DHCP will provide the dynamic IP addresses with an expiration date.

What is a Dynamic VS Static IP Address?

The typical network setup is dynamic by default. This means that your router’s DHCP server will provide an address that is not guaranteed to be the same after a device or network is restarted. Each dynamic address is assigned with an expiration date. Which means that the assigned IP address will only be guaranteed for a limited time. Once that expiration date is met, and that device is no longer using it, the IP address is free to be re-assigned to another device. To prevent an IP address from changing or being used by another device one can setup a static IP address.

What is a static IP address?

Simply put, a Static IP address is one that does not change after devices or network are restarted. For example, you can assign a static IP address of to your POSIM Server that will not change. So your client computers can consistently use that address to connect to the server.

How can I give my servers or devices a static IP address?

There are a few main methods used to assign a Static IP address to a device. We are, unfortunately, not able to provide specific instructions for how to set this up with any particular router or networking equipment. There are simply too many possible hardware combinations to provide that kind of detail. However, most networking companies will provide support for these features in their devices. We are providing this information for you to have a better understanding and to be able to more effectively communicate with a network professional.

Set Device IP Manually outside of DHCP Range

As mentioned previously, a DHCP Server will be set up to provide a range of dynamic IP addresses. In the example above the range was from to Essentially we are saying that there are 99 potential devices that will be on our network. Most routers are able to handle many more devices than that. On a computer or device, you can basically request an IP address. If the requested address is within the range of the DHCP server there is the potential that the requested address is already taken. So to get around this, you can assign an IP address that is outside the DHCP range. Continuing the example above, you could set the manual address for a device to be which is safely outside the DHCP range, but within the routers limits. Typically a router can handle up to 254 addresses within the same subnet. In this case, the max address could be As you can see, this provides plenty of addresses that can be set outside the DHCP range. As long as you are setting up your devices with a unique address this method is fairly easy and works great.

Set Router’s DHCP Server to Assign a Static IP

Every device’s network adapter has a MAC, or Media Access Control, address. (MAC addresses are also known as hardware addresses or physical addresses.) This is comparable to the GPS coordinates of a physical location. A MAC address has the form of “01-23-45-67-89-ab” or “01:23:45:67:89:ab”. There are basically six groups of two hexadecimal digits separated by hyphens (-) or colons (:). This address uniquely identifies a network adapter such as an ethernet port or wifi chip. This MAC address can be used to assign a static IP to the device. Basically, you would log into your routers configuration settings and tell the DHCP server that when it sees a specific MAC address to assign the device with a specific IP address. When a device tries to connect to a network, it tells the router its MAC address and the router will either assign new dynamic IP, or it will assign a specific static IP address if the MAC address matches the one setup.

Set Router’s DHCP Server lease expiration to maximum

Many routers provide an option for setting the DHCP server lease expiration period. For example, the expiration could be set to months or even years. This means that once the DHCP server hands out an IP address it won’t be set to expire for a long time and it will protect the address for a specific device. Just to clarify, this method will not technically be providing static IP addresses, but it will prevent the dynamic addresses from expiring and this can dramatically decrease the likelihood of an IP address changing. It may also be helpful to plug your router into a UPS, or Uninterruptible Power Supply, which is basically a backup battery so that if the power goes out, or flickers, the router will stay on and will be able to keep its list of DHCP addresses and their lease expiration.