diff --git a/Frequently-Asked-Questions.md b/Frequently-Asked-Questions.md
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@@ -20,4 +20,14 @@ But suppose your network is entirely constrained to a single geographic region a
 
 What happens when a previously defined IP stops showing up in a scan? Should it be deleted? The host might actually still exist, though. Maybe we should mark it as "previously used" somehow. But then we're still using a database record to track an IP that might not even exist. And should we automatically add new IPs that pop up? What if they're not supposed to be there?
 
-All this boils down to a single concept: NetBox is intended to represent the **intended** state of the network, as defined by humans, whereas scanning a live network reflects only its **actual** state at that moment. When you attempt to define the correct state by referencing the actual state with no intermediate process of validation, bad things happen.
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+All this boils down to a single concept: NetBox is intended to represent the **intended** state of the network, as defined by humans, whereas scanning a live network reflects only its **actual** state at that moment. When you attempt to define the correct state by referencing the actual state with no intermediate process of validation, bad things happen.
+
+# Why does NetBox Require Every IP to Have a Mask?
+
+The subnet mask is part of an IP address: You cannot assign an IP address to an interface in the real world without also specifying its subnet mask. A device uses its interface's mask to determine the boundary of its layer two domain.
+
+In keeping with its core design philosophy of directly modeling the real world, NetBox requires that the subnet mask be stored along with each IP address. This allows users to validate real-world configurations against NetBox data in a very efficient manner, as well as aiding the detection of invalid addresses within NetBox.
+
+Omitting the mask from the IP address model would require us to make dangerous inferences about each IP address. For example, if you are given only the IP address 192.0.2.123, you cannot determine its network without additional information. You could look for its most-specific parent prefix: let's assume 192.0.2.0/24 has been created. But that doesn't necessarily indicate that our IP has a /24 mask. That /24 might be a smaller container used for administrative organization inside a larger parent, or there might be a more-specific /25 or /26 prefix missing from NetBox. Or it could be a loopback IP that should have a /32 mask.
+
+Treating an IP address and its subnet mask as an atomic unit ensures a much greater degree of efficiency and accuracy.
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