DHCP Server Configuration

Overview

• DHCP (Dynamic Host Configuration Protocol) servers assign IP addresses to devices on a network.
• Essential for network management, especially when handling many devices.

Key Configuration Settings for DHCP Server

IP Address Range

• Define the range of IP addresses the DHCP server assigns.
• Associated subnet mask is required.

Lease Duration

• Determines how long a workstation retains the same IP address.

DNS and Gateway Settings

• Configure DHCP server with DNS server settings.
• Default gateway setting for routing traffic.
• Optional settings like VoIP server configurations.

DHCP Address Pool

• Pool of addresses configured within the DHCP server.
• Addresses are assigned dynamically from this pool.

DHCP Reservations and Exclusions

• Reservations: Permanent assignments of IP addresses to specific devices.
• Exclusions: Certain IP addresses within the range are not assigned.
• Static Assignments: Also known as DHCP reservations or static DHCP.

Example Configuration

Windows Server DHCP

• Example scope: 165.245.44.0.
• Address pools, leases, reservations, and scope options.

Embedded Router DHCP

• Example start address: 10.10.10.2, end address: 10.10.10.100.
• Lease time in seconds (e.g., 86,400 seconds = 24 hours).
• Gateway and DNS configurations.

Dynamic vs. Static Assignments

• Dynamic Assignment: Temporary IP assignments from the DHCP pool.
• Static Assignment: Permanent assignment; based on device MAC address.

Lease Renewal Process

Lease Timers

• T1 Timer: Halfway through lease duration (e.g., 4 days of an 8-day lease), device checks in to renew.
• T2 Timer: At 87.5% of lease time (e.g., 7 days of an 8-day lease), if T1 fails, device tries to rebinding with another DHCP server.

Rebinding

• If the original DHCP server is down, rebinding allows retention of the IP by contacting another DHCP server.

Visual Process Example

• Lease time: 8 days
• Check-in and renewal at T1 (4 days).
• Rebinding phase if no contact with original DHCP server.

Key Concepts

• Lease Time: Duration an IP is held before renewal.
• Dynamic Pool Management: Efficient handling of IP addresses.
• Redundancy: Multiple DHCP servers ensure continuous IP address availability.