IP Scheme

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Zach

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When someone says they want to understand the IP scheme within a network, they are referring to the structure and organization of how IP addresses are assigned and used in that network. This helps them identify devices, troubleshoot issues, and plan network expansion efficiently.

Key Aspects of an IP Scheme

1️⃣ IP Address Ranges – What subnet(s) are being used?

• Example: 192.168.1.0/24 or 10.10.0.0/16
• Determines how many devices (hosts) can exist in the network.

2️⃣ Subnetting & CIDR Notation – How is the network divided?

• Example: A company may split 10.10.0.0/16 into multiple /24 subnets for departments.
• Network portion vs. host portion of each address.

3️⃣ Private vs. Public IPs – Are private IPs being used for internal devices?

• Most local networks use private IPs (e.g., 192.168.x.x, 10.x.x.x).
• Public IPs are assigned for internet-facing devices.

4️⃣ Default Gateway – What is the route to external networks?

• Example: If the subnet is 192.168.1.0/24, the default gateway is likely 192.168.1.1.

5️⃣ VLANs (Virtual LANs) – Are there separate IP schemes for different groups?

• Example:
• VLAN 10 (Workstations): 10.10.10.0/24
• VLAN 20 (Servers): 10.10.20.0/24
• VLAN 30 (VoIP Phones): 10.10.30.0/24

6️⃣ Static vs. DHCP Assigned IPs – Which addresses are manually assigned, and which are dynamic?

• Static IPs for servers, printers, and network equipment.
• DHCP pool for end-user devices.
• Example:
• Static: 10.10.1.1 - 10.10.1.50
• DHCP Pool: 10.10.1.51 - 10.10.1.200

7️⃣ DNS Servers – What IP addresses are assigned for name resolution?

• Example:
• Internal DNS: 10.10.5.5
• External DNS: 8.8.8.8 (Google DNS)

8️⃣ Special Addressing Considerations – Are there reserved addresses?

• Reserved for future use or special functions.
• Loopback (127.0.0.1), broadcast (x.x.x.255), APIPA (169.254.x.x).

Why is Understanding the IP Scheme Important?

✅ Helps with troubleshooting (e.g., identifying incorrect IP assignments).

✅ Assists in scaling the network efficiently.

✅ Ensures security and proper segmentation (e.g., separating guest Wi-Fi from internal traffic).

✅ Prevents IP conflicts and routing issues.

How to Find the IP Scheme in a Network

📌 Run ipconfig /all (Windows) or ifconfig / ip a (Linux) to see your device’s network settings.

📌 Check the DHCP server for dynamic address pools.

📌 Look at the router/firewall settings for subnet configurations and VLANs.

📌 Use tracert or ping to map connections between devices.

Example: A Simple Enterprise IP Scheme