The DHCP server assigns an address to a DHCP client for a limited period of time. The limited life of the address is called a lease. The client can return the address to the server at any time, but must request an extension from the server to retain the address longer than the time permitted. The server automatically reclaims the address after the lease expires if the client has not requested an extension.

Dynamic allocation is useful in a large distributed network where many systems are being added and deleted. Unused addresses are returned to the pool of addresses without relying on users or system administrators to take action to return them. Addresses are only used when and where they're needed. Dynamic allocation allows a network to make the maximum use of a limited set of addresses.

For obvious security reasons, node admin privileges must be authorized by your node director. If you are a new customer, visit our request form. If you are an existing DHCP Customer, your node's domain administrator can grant you sub-administrator privileges.

An administrator has full control including user permissions of a domain, while a Sub-Administrator can only add/remove/modify host settings in the domain.

You may have forgotten to register your host for DHCP service at this site. We allow you to temporarily boot a new host to the network as an unregistered host so you can access this web site and register your host for DHCP service. Registration of all DHCP clients allows us to keep track of IP address usage. It enables us to keep an eye on networks that might need extra capacity to accommodate growing user bases, diagnose problems, audit traffic, and generally help you manage your network. It's just good policy.

To enforce this policy, we automatically register unregistered hosts as 'Excluded' hosts if we detect that they've been hanging around for six hours or longer. This action excludes the unregistered host from DHCP service and forces you to visit this site to 'unexclude' it. Here's how:

1. Go to the main DHCP page and select 'Edit a previously registered host's record' (because we've already registered your host as an exclusion).
2. Log in.
3. Query for your host using any one of the following options:
   • Ethernet Address = {your client's Ethernet (MAC) address}, or
   • Hostname = {your client's hostname} AND Status = 'Excluded', or
   • Hostname = {your client's subnet} AND Status = 'Excluded', where 'subnet' is the third octet of the fully qualified subnet on which your client resides (128.205.subnet.0).
   When the script returns a DHCP record, your excluded client's Hostname will be '{hostname}_{subnet}', where 'subnet' is the third octet of the fully qualified subnet on which your client resides (128.205.subnet.0).
4. Edit this DHCP record to meet your specifications. Be sure to set the Status field to 'Active'.
5. Reboot the machine and you should be all set.

The DHCP client database already contains a record with your hostname/domain name pair. Two machines cannot exist within one domain with the same hostname. For you, this means one of two things: somebody beat you to the hostname that you wanted, or somebody already tried to register the host that you're trying to register now. Maybe the other person registered it with an incorrect mac address.

1. Query the database for the hostname/\domain name combination that you wanted to add. If a machine with that name already exists, you have found the source of conflict.
2. If you're absolutely certain that the host record with your intended hostname is a mistake, delete the impostor and take that hostname for yourself. Otherwise, if your intended hostname is legitimately being used by another host, register your host with a different hostname.

It depends which operating system you're running:

• Windows Business-Grade OSes (NT/2000/XP Professional)
  1. Open a Command Window
     • Windows NT: Start > Programs > Command Prompt
     • Windows 2000: Start > Programs > Accessories > Command Prompt
     • Windows XP Professional: Start > All Programs > Accessories > Command Prompt
  2. To release your IP address, type: ipconfig /release
  3. To renew your IP address, type: ipconfig /renew
  4. Type: exit
• Windows Consumer-Grade OSes (95/98/ME/XP Home Edition)
  1. Open a Command Window
     • Windows 98: Start > Programs > MS-DOS Prompt
     • Windows ME: Start > Programs > Accessories > MS-DOS Prompt
     • Windows XP Home Edition: Start > All Programs > Accessories > MS-DOS Prompt
  2. To release your IP address, type: ipconfig /release_all
  3. To renew your IP address, type: ipconfig /renew_all
  4. Type: exit