Video: What is an IP Address? // You SUCK at Subnetting // EP 1 (NetworkChuck). Embedded from YouTube in privacy-enhanced mode; all rights belong to the creator.
Every device on a network needs an address. Understanding how those addresses are structured — and how networks are carved into subnets — is foundational for anyone working in IT, DevOps or cloud infrastructure.
IPv4 in one paragraph
An IPv4 address is 32 bits, written as four decimal octets: 192.168.1.10. That allows about 4.3 billion addresses — far too few for today's internet, which is why we rely on NAT (many private devices sharing one public address) and are steadily adopting IPv6.
Public vs private
RFC 1918 reserves three ranges for private networks that are never routed on the public internet:
| Range | CIDR | Typical use |
|---|---|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 | Enterprises, cloud VPCs |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 | Docker, mid-size networks |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 | Home and small-office routers |
Your router translates between these and the public address you can see with our What Is My IP tool.
CIDR and subnet masks
CIDR notation 192.168.1.0/24 says the first 24 bits identify the network and the remaining 8 bits identify hosts. The equivalent subnet mask is 255.255.255.0 — 24 ones followed by 8 zeros in binary. Hosts per subnet = 2(32 − prefix), minus 2 reserved addresses (network and broadcast).
| Prefix | Mask | Usable hosts |
|---|---|---|
| /30 | 255.255.255.252 | 2 |
| /28 | 255.255.255.240 | 14 |
| /26 | 255.255.255.192 | 62 |
| /24 | 255.255.255.0 | 254 |
| /22 | 255.255.252.0 | 1,022 |
| /16 | 255.255.0.0 | 65,534 |
Worked example
You need four subnets of at least 50 hosts from 10.20.0.0/24. 50 hosts needs 6 host bits (64 addresses, 62 usable), so each subnet is a /26: 10.20.0.0/26, .64/26, .128/26 and .192/26. Verify each in the subnet calculator.
Cloud planning tips
- Pick a large, unusual private block for each VPC (e.g. 10.42.0.0/16) so future VPN or peering connections don't overlap.
- Cloud providers reserve extra addresses per subnet — AWS reserves 5 — so size generously.
- Kubernetes needs separate ranges for nodes, pods and services; pods consume addresses fast.
IPv6 essentials
IPv6 addresses are 128 bits written in hex groups: 2001:db8:85a3::8a2e:370:7334 (:: compresses consecutive zero groups). The standard subnet for a LAN is a /64 — 18 quintillion addresses — so the scarcity mindset of IPv4 simply doesn't apply.
Try the tools
Subnet / CIDR Calculator
Network, broadcast, host range and mask for any IPv4 CIDR.
What Is My IP Address
See your public IP, ISP, location and time zone.
Number Base Converter
Decimal ⇄ hex ⇄ binary ⇄ octal with big-number support.