What is the Slash Notation at the End of IP Addresses (/8, /16, /24)?

For those without a Computer Science Degree.

Travis Rodgers
3 min readJul 25, 2020
Photo by Bekky Bekks on Unsplash

If you have a CS degree, you may want to pass on this elementary article.

No talk about masks or octets here.

But for those software developers who lack Computer Science fundamentals, and have ventured into the cloud or networking spaces, this may be a question you’ve left unanswered for a while now.

I know I did. Programming excites me. Networking scares me. But as I was pushed into developing in the Cloud (Azure specifically), I didn’t have a choice.

Ram, Memory, Throughput, Virtual Networks, Subnets, I/O, Gateways, etc. etc. Yikes.

So what’s up with that “/”

When it comes to IP addresses in the cloud we see things like 192.168.10.0/24 or 10.1.0.0/16. And often we have to make a decision when architecting cloud solutions.

So what does this number after the slash mean in simple terms?

Well, in an IPv4 address space, there‘s a total of 32 bits.

The number that comes after the slash tells us how many bits are part of the network address (and ultimately what is left over, we can assign).

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Travis Rodgers

Self-taught developer writing about all I've learned along the way. Website at https://travis.media | YouTuber @ youtube.com/travismedia