DHCP Dynamic Host Configuration Protocol

What is DHCP?  It does name resolution (one more?!) DNS resolves IP numbers and FQDN WINS resolves NetBIOS names and IP numbers ARP resolves IP numbers and MAC addresses (outgoing packets) DHCP resolves IP numbers and MAC addresses dynamically  The Windows BootP BootP is a table of IP numbers and MAC addresses on a server DHCP is a dynamic BootP

How does it work? DHCP CLIENT DHCP CLIENT DHCP SERVER DHCP DATABASE MAC address MAC address, IP#, lease time DHCP discover DHCP offer IP#, lease time IP scope DHCP request IP#, MAC address IP#, lease time DHCP ack (1) (2) (0) Scope - a range of IP addresses IP lease - the IP# is assigned temporarily Reserved IP - servers are assigned fixed IP addresses

Pros and Cons  Pros simplifies the task of assigning IP numbers to each machine in the network makes easy to add, remove or move a host can assign defaults: default gateway, domain name, DNS server, WINS server (if any). ability to have fewer IP# than hosts  Cons if DHCP server is down, all hosts are down hard to keep information on free and used IP #

Multi-DHCP networks  No server coordination each subnet can only have one scope (continuous, but you can exclude some IP addresses), but you can create DHCP servers with non- overlapping scopes to the same subnet (not MS party line)  Backup and fault tolerance DHCP makes an hourly backup of its database it can recover itself, but you should do a backup of its backup if you think something is wrong copy the DHCP backup before stopping it (at shutdown does another backup).

Install and setup  Install open network in control panel, select services add MS DHCP Server, press OK and closeMS DHCP Server system will need to reboot, do it when re-starts DHCP is installed and started as a service  Setup open DHCP Manager and select create scopeDHCP Manager enter the range of IP# and exclusions as shown shown select options, global and enter defaultsdefaults finally assign static IP numbers to defaultsstatic IP numbers

DHCP and IPCONFIG  IPCONFIG/ALL FQDN, servers (DNS, WINS), node type, etc NIC description, MAC address, IP address, gateway, subnet mask  To handle leases IP CONFIG/RENEW [adapter] IP CONFIG/RELEASE [adapter] if no adapter name is specified, then the IP leases for all adapters bound to TCP/IP will be released or renewed.