# The Essential Subnetting Cheat Sheet

October 28, 2015 | Views: 27437

While studying for CCNA many years ago, I created this document to assist me with subnetting.  Hope you find this information helpful.

Address Space – 32 bit IPV4

 11111111 11111111 11111111 11111111

 28-2=254 27-2=126 26-2=62 25-2=30 24-2=14 23-2=6 22-2=4 21-2=0 128 64 32 16 8 4 2 1 1 = 128/25 0 0 0 0 0 0 0 1 1=192/26 0 0 0 0 0 0 1 1 1=224/27 0 0 0 0 0 1 1 1 1=240/28 0 0 0 0 1 1 1 1 1=248/29 0 0 0 1 1 1 1 1 1=252/30 0 0 1 1 1 1 1 1 1=254/32 0 1 1 1 1 1 1 1 1=255

Step 1 – Draw Grid

Step 2 – Count on fingers by 2 from 2 (2,4,8,16,32,64,128,256)

Step3 – 2n-2

Step4 – “Can I draw the line here?”

Step5 – Magic number sequence (bit * wire number)

 N 128 64 32 16 8 4 2 1 1xN 1 – 128 1 – 64 1 – 32 1 – 16 1 – 8 1 – 4 1 – 2 1 – 1 2xN 2 – 256 2 – 128 2 – 64 2 – 32 2 – 16 2 – 8 2 – 4 2 – 2 3xN 3 – 192 3 – 96 3 – 48 3 – 24 3 – 12 3 – 6 3 – 3 4xN 4 – 256 4 – 128 4 – 64 4 – 32 4 – 16 4 – 8 4 – 4 5xN 5 – 160 5 – 80 5 – 40 5 – 20 5 – 10 5 – 5 6xN 6 – 192 6 – 96 6 – 48 6 – 24 6 – 12 6 – 6 7xN 7 – 224 7 – 112 7 – 56 7 – 28 7 – 14 7 – 7 8 – 256 Up to 16 Up to 32 Up to 64 Up to 128 Up to 256?

 Class IP Range Subnet Private Address Range Class A 1 – 126 255.0.0.0 10.0.0.0 – 10.255.255.255.255 Class B 128 – 191 255.255.0.0 172.16.0.0 – 172.31.255.255 Class C 192 – 223 255.255.255.0 192.168.0.0 – 192.168.255.255 Class D 224 – 239 Multicast Class E 240 – 255 Experimental

 OSI Model TCP/IP Model TCP/IP Protocols Application Application HTTP, SMTP, POP3 Presentation Session Transport Transport (TCP/UDP TCP, UDP Network Internet (IP) IP Data – Link Network Access Layer (Ethernet/FDDI) Ethernet, Frame-Relay, PPP Physical

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1. Excellent information, thank for sharing!

2. I am studying for the CCNA. I get subnetting, but I do not understand this sheet exactly. Wish I could as it would probably help speed it up.

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