What is an IP Address?
What is an IP Address?
An IP address is a unique logical address used to identify a device on a network and allow communication between devices.
There are two main versions:
- IPv4
- IPv6
🔹 IPv4 (Internet Protocol version 4)
📌 Format
- 32-bit address
- Written in decimal with dots
- Example:
192.168.1.1
📌 Structure
- 4 octets (8 bits each)
192 . 168 . 1 . 1
- Total addresses: ~4.3 billion
📌 Address Classes (Old method)
ClassRangeA1.0.0.0 – 126.0.0.0B128.0.0.0 – 191.255.0.0C192.0.0.0 – 223.255.255.0
Today we mainly use CIDR (e.g. /24, /16)
📌 Private IPv4 Addresses
Used inside LAN:
- 10.0.0.0 – 10.255.255.255
- 172.16.0.0 – 172.31.255.255
- 192.168.0.0 – 192.168.255.255
📌 Key Features
✔ Widely used
✔ Easy to understand
❌ Address exhaustion
❌ Needs NAT
🔹 IPv6 (Internet Protocol version 6)
📌 Format
- 128-bit address
- Written in hexadecimal with colons
- Example:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
📌 Shortened Format Rules
- Remove leading zeros
- Replace consecutive zeros with ::
Example:
2001:db8::1
📌 Address Types
TypeDescriptionUnicastOne-to-oneMulticastOne-to-manyAnycastNearest device
🚫 No Broadcast in IPv6
📌 Key Features
✔ Huge address space (≈ unlimited)
✔ No NAT required
✔ Built-in security (IPsec)
✔ Faster routing
🔄 IPv4 vs IPv6 (Quick Comparison)
FeatureIPv4IPv6Address Size32-bit128-bitFormatDecimalHexadecimalNATRequiredNot requiredBroadcastYesNoSecurityOptionalBuilt-inSpeedSlowerFaster
🎯 Example (Home Network)
- IPv4: 192.168.1.10
- IPv6: 2001:db8::10
📚 Exam Tip (CCNA / Networking)
- Know private IPv4 ranges
- Understand IPv6 shortening
- Remember: IPv6 has no broadcast
- IPv6 uses Neighbor Discovery Protocol (NDP) instead of ARP
If you want, I can also explain:
- ✅ IPv4 Subnetting
- ✅ IPv6 Address Types in depth
- ✅ IPv4 vs IPv6 interview questions
- ✅ Cisco router configuration (IPv4 & IPv6)