Configuring a DHCP Server

Key Components of DHCP Configuration

• IP Address Range:

  • Define the range of IP addresses the DHCP server will assign.
  • Associated subnet mask required for the IP address range.

• Lease Duration:

  • Configuration on how long a workstation retains the same IP address.

• DNS Server Settings:

  • Configure DHCP server to provide DNS server IP address, default gateway, and any additional options like VoIP servers.

DHCP Address Pools

• Address Pools:

  • A DHCP server assigns IP addresses from a pre-configured pool.
  • Example: A subnet pool could be /24, allowing assignment within that range.

• Reservations and Exclusions:

  • DHCP Reservations: Ensure a device always receives the same IP address, typically using the device's MAC address.
  • Exclusions: Certain IP addresses can be excluded from the available pool.

DHCP Lease and Renewal Process

• Dynamic Assignment:

  • Devices receive a dynamically assigned IP address from the DHCP pool.
  • IP addresses are reassigned after lease period expiration.

• Automatic Assignment:

  • DHCP servers often remember previously assigned IP addresses and may reassign them if still available.

• Lease Timers:

  • T1 Timer:
    • Occurs at 50% of lease time.
    • Device checks in to renew lease.
  • T2 Timer:
    • Occurs at 87.5% of lease time.
    • Attempts rebinding with any DHCP server if the original is unavailable.

DHCP Server Examples

• Windows Server:

  • Includes functionalities like viewing address leases and configuring reservations.
  • Supports options for additional IP configurations, such as VoIP gateways.

• Embedded Router:

  • Simpler interfaces, often used in home or small office settings.
  • Web-based management of DHCP services.

Static DHCP Assignment

• Static DHCP/Reservation:
  • Ensures certain devices always receive the same IP address based on MAC address.
  • Known as static assignments or IP reservations.

Practical Example:

• Soho Network DHCP Server:
  • Demonstrates configuration with MAC addresses for static IP assignments.
  • Examples: Device "Prometheus" with IP 192.168.1.6.

Lease Renewal Visual Example

• Lease Time Configuration:
  • Example of an 8-day lease time with T1 (4 days) and T2 (7 days) timers.
  • If original DHCP server is unavailable, rebinding occurs with a redundant server after T2 timer.