Wildcard Masks

If you understand Subnetting, then you probably know that the CIDR notation of /24 correlates to the Subnet Mask of But did you also know both of those correlate to the Wildcard Mask of

This video picks apart Wildard Masks, what they are, and how they are used. We’ll cover the following concepts:

  • Basic Definition of Wildcard Masks
  • Binary Conversions (CIDR to Subnet to Wildcard)
  • Special Wildcard Masks: /32 and /0
  • Easier Conversions between Subnet Masks and Wildcard Masks
  • What can you do with a Wildcard Mask?
  • Determine if two IP addresses are in the same Subnet
  • Identify IP addresses in a particular Subnet
  • How is a Wildcard Mask different from a Subnet Mask?
  • Discontiguous Wildcard Masks

This video is a follow up to a video I released earlier in the month discussing Binary. Both this video on Wildcard Masks, and the aforementioned Binary videos are pre-cursors to a video on Access Control Lists (ACLs) that I am working on.

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