Subnetting

cidr.xyzcidr.xyz

Reserver IP addresses

In AWS, the first 4 and last 1 IP addresses in a subnet are reserved

Let’s say, for 10.0.0.0/24

• 10.0.0.0 – 10.255.255.255 (10/8 prefix)
• 172.16.0.0 – 172.31.255.255 (172.16/12 prefix)
• 192.168.0.0 – 192.168.255.255 (192.168/16 prefix)

Private IP ranges

• 10.0.0.0 – 10.255.255.255 (10/8 prefix)
• 172.16.0.0 – 172.31.255.255 (172.16/12 prefix)
• 192.168.0.0 – 192.168.255.255 (192.168/16 prefix)

172.29.10.0/24  subnetting from /24 to /28

Subnet	CIDR	Description
Sub1	172.29.10.0/28	Public AZ A
Sub2	172.29.10.16/28	Public AZ B
Sub3	172.29.10.32/28	DIR AZ A
Sub4	172.29.10.48/28	DIR AZ B
Sub5	172.29.10.64/28	EXT AZ A
Sub6	172.29.10.80/28	EXT AZ B
Sub7	172.29.10.96/28	PROXY AZ A
Sub8	172.29.10.112/28	PROXY AZ B
Sub9	172.29.10.128/28	FSx AZ A
Sub10	172.29.10.144/28	FSx AZ B
Sub11	172.29.10.160/28	RDS AZ A
Sub12	172.29.10.176/28	RDS AZ B
Sub13	172.29.10.192/28	UPU AZ A
Sub14	172.29.10.208/28	UPU AZ B
Sub15	172.29.10.224/28	FFC AZ A
Sub16	172.29.10.240/28	DEV AZ B