IP address

🧠 What Is an IP Address?

• Definition: A unique numerical label assigned to every device on a network using the Internet Protocol.
• Purpose:

1. Identification – tells who the device is.
2. Location – tells where it is on the network.
   • Analogy: Like your home address—ensures the message (data) reaches the correct destination.

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🌍 Two Main Versions of IP

Feature	IPv4	IPv6
Bit Length	32-bit	128-bit
Format	192.168.0.1	2001:0db8:85a3:0000:0000:8a2e:0370:7334
Total Addresses	~4.3 billion	2¹²⁸ (virtually unlimited)
Written As	Decimal (4 octets)	Hexadecimal (8 hextets)
Why IPv6?	IPv4 ran out of available addresses	Solves shortage, adds better security & routing

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🧩 Structure of IPs

• IPv4: Four octets separated by dots → e.g. 192.168.1.5

  • Each octet = 8 bits = value between 0–255.

• IPv6: Eight hextets separated by colons → e.g. 2001:db8::1

  • Each hextet = 16 bits = value between 0000–FFFF.

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🏠 Public vs Private IPs

Type	Example	Used For	Accessible From Internet?
Private	192.168.x.x, 10.x.x.x	Inside local networks (home, office)	❌ No
Public	54.167.118.5 (AWS EC2, etc.)	For internet access, websites, servers	✅ Yes

Check yours:

• Private: ipconfig (Windows) / ifconfig (Linux/Mac)
• Public: visit whatismyip.com

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🔄 Network Address Translation (NAT)

Purpose:
Translates private IPs → public IPs so multiple devices share one public address.

How it works:

1. Your device (192.168.1.10) sends a request to Google.
2. NAT router replaces it with your public IP (like 73.101.22.5).
3. Response from Google returns → NAT routes it back to 192.168.1.10.

Benefits:

• Saves public IP space.
• Hides internal network → adds security.

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🔢 Static vs Dynamic IPs

Type	Assigned By	Changes?	Typical Use
Static	Manually	No	Servers, DNS, websites
Dynamic	DHCP	Yes	Home/office devices

In AWS: Elastic IPs = static IPs.
Regular EC2 public IP = dynamic (changes on reboot).

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💡 DevOps Connection

DevOps Context	Role of IP
AWS EC2	Public IP identifies your instance; private IP used for internal VPC traffic.
Load Balancers / NAT Gateway	Manage traffic between private and public subnets.
CI/CD Servers (Jenkins, GitHub Webhooks)	Require static IPs or DNS mapping for stability.
Monitoring / SSH / Networking	IP helps identify nodes, agents, pods, and network traffic.