If you’re a network technician trying to assign an IP address to a device, then APIPA can either be a life saver or a job hazard.

It can be annoying and inconvenient when your back is up against the wall. Or it can save you a headache if you’re not careful with how you assign your IP addresses to your devices.

APIPA stands for Automatic Private Addressing, and it’s a Windows feature that automatically assigns an IP address to a device or system when one can’t be obtained automatically. So if you see an IP address with a range between 169.254.0.1-169.254.255.254, then APIPA is being used. Don’t question this.

HOW AN IP ADDRESS IS ASSIGNED AUTOMATICALLY

As you know, every device on a network NEEDS an IP address. The IP address can either be STATIC or DYNAMIC.

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TERM ALERT: There are two types of IP addresses that you should commit to memory for the N10-008 exam – STATIC AND DYNAMIC.

A STATIC IP address is an IP address that does not change unless the user changes it.

A DYNAMIC IP address constantly changes over time.

Of course, there is way more to it than this basic explanation. But this is just an introduction of the terms. To learn more about static vs dynamic IP addresses, NordVPN has a great article about the subject. READ MORE..

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Two devices can’t be assigned the same IP address, the same way two different families can’t truly reside at the same address without a bunch of conflicts. Of course there are exceptions, but for the most part it would be difficult.

This is where dynamic IP addressing comes in. A DHCP server dynamically assigns IP addresses in order to prevent a device being assigned an IP address that’s assigned to another. Dynamic IP addressing is how an IP address is assigned automatically.

WHAT IS A DHCP SERVER?

A DHCP server is a network server that automatically assigns your IP addresses to your devices and default gateways within a network.

During the boot sequence, a host (like a PC or laptop, for example) will search for a DHCP server on a network. If it can’t find the DHCP server, then the device is assigned an APIPA address range until a DHCP server becomes available.

Using Address Resolution Protocol, your Operating System will search your network to ensure that your device isn’t using APIPA because another device is using the same IP address. Again, two devices on a network can’t use the same address, and it’s ARP’s job to double check that issue.

Matthew Kafami of CBT Nuggets says this can particularly come in handy when troubleshooting your DHCP server.

While APIPA can prevent you from using duplicate IP addresses, it can do other beneficial things in a networking environments. Matthew Kafami writes,

One of the main benefits of APIPA is the automatic assignment of an IP address, which removes the hassle of figuring out which IP addresses are available for use and manually assigning your device a static IP address. This also reduces the risk of you or someone else on your network accidentally taking an IP already in use. Another benefit to using an APIPA address is the ability to continue some business functions during a DHCP outage.

CBT Nuggets

APIPA LAB

If you would like to dive further into this topic, I advise you read the CBT Nuggets from Matthew Kafami. It’s a great article that gives you exactly what you need to know about APIPA for the purposes of studying for a certification test.

I have also intentionally jacked up a lab on the next page. That way you can see APIPA in action.

Click the next page to begin the lab.