Dynamic Host Configuration Protocol (DHCP)

• "The most important protocol that allows you to communicate with devices"
  • Allows devices to automatically obtain IP addresses for a network

DHCP Overview

• Dynamic addressing services

  • Anytime a new client joins a network it is going to have to do a request and is like a shouting to the universe to find its destination

  • The discovery, the announcement and the checkout process

  • IP address 10.1.1.5

  • Subnet mask 255.255.255.0

  • Gateway

    • Will get us out for anywhere we want to leave

  • Domain Name Server

    • We tend to use internal DNS servers

  • File server for OS / Configuration

  • IP Options

    • Look for DHCP options
    • Not every client or every server supports every option

  • Supports Reservations

    • MAC addresses will be part of requests so you can add devices that are stateless or can have static IPs getting the same IP address each and every time.

DHCP Server

• Pool of addresses, Scope
• Gateway
• DNS
• TFTP
• Additional Options
• Maintain good logging
  • MAC -> IP

DHCP Client

• OS & Device independent
• May have a reservation (MAC)
• DNS may be manual
  • Typically is best left to automatic
• Manual configuration can cause conflicts
  • If you type an IP that is inside of the scope that server may try to handle it, but lot of software firewalls block ICMP so if you ping to see if somebody there, if you block ICMP you break the ability to find duplicate address discovery