Static vs Dynamic Host Address Configuration


  • Using static addressing requires an administrator to visit each computer to manually enter the configuration information for that host
    • if host moves, must manually reconfigure it
    • administrator must keep track of which IP addresses have been allocated to avoid issuing duplicates
    • In a large network, configuring IP statically on each node can be very time consuming and prone to errors that can potentially disrupt communication on the network
    • typically only assigned to systems with a dedicated functionality
      • E.g., router interfaces or application servers that need fixed IP addresses

Dynamic Host Configuration Protocol

Automatic Private Addressing

  • Hosts have a failover mechanism for when the IP configuration specifies use of a DHCP server but the host cannot contact one
    • computer selects an address at random from the range 169.254.0.1 to 169.254.255.254
      • Microsoft calls this automatic private IP addressing (APIPA)
        • others call this link local
      • When a host is using an APIPA address, it can communicate with other hosts on the same network that are using APIPA
        • but cannot reach other networks or communicate with hosts that have managed to obtain a valid DHCP lease
    • some hosts leave the IP unconfigured
    • some hosts use 0.0.0.0