Reaching Others University at Buffalo - The State University of New York
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About DHCP

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.

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.

Why We Use DHCP at UB

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.

Requesting Access

Permissions in the old DNS/DHCP tools don't directly map to the new tool.

If you don't currently have access to the system or your permissions are incorrect, submit a request.

We will need:

  • Your Name
  • Your Node Affiliation
  • A list of UBITNames that also need access
  • Any non-obvious domains that you control or manage (we can usually figure this out, but you know best)

Administrative Login

  1. In a Web browser, visit https://dnsmgt.buffalo.edu/
  2. Use your UBITName and password as credentials for accessing the system.
  3. You will be given access only to the subnets and DNS zones that are in use by your area.

Dashboard

Upon login, you will be shown the dashboard. This area displays general information about the DNS/DHCP system as well as providing a table of contents to the various administrative sections.

This view is customizable and can contain any number of widgets. Some of the more useful components are:

  • DHCP Statistics
  • DDNS Statistics
  • Ranges over Threshold

To add a new component to your dashboard:

  1. From the Dashboard, select Add Content in the upper right-hand corner.
  2. When the component toolbar appears, drag and drop the component onto the Dashboard page where you'd like it to appear.
  3. Select Close.
  4. You may be prompted for more information inside the individual component.

Static Hosts versus Roaming Hosts

The Infoblox device makes a distinction between hosts on the network by how they are configured for network access and how they manage their DNS updates. The 2 main types of hosts are Static Hosts and Roaming Hosts.

  • A Static Host is an entry in DNS that maps a Fully Qualified Domain Name (FQDN) (hostname.domain.buffalo.edu) to an IP address for a given device. This is commonly needed when a device requires a specific IP address to be accessed by other devices in a given network such as a file server or Web server.
  • A Roaming Host is an entry in DHCP that maps a given FQDN to a MAC address (00:11:22:33:44:55). This is commonly needed when a device requires a specific hostname to be accessed by other devices in a given network, but will be continuously changing IP addresses. Registering a roaming host entry will ensure that a FQDN will correspond to a unique device regardless of its network or IP address. This is the type of entry for most devices at UB.

Administrative Functions

Creating a Roaming Host Entry

  1. Navigate to the Data Management Tab and then select the DHCP sub-tab.
  2. Select the dropdown menu next to the Add button on the left-hand side.
  3. Select Roaming Host.
  4. Select Add Roaming Host and click Next.
  5. Fill in the hostname (NOT the FQDN) in the Name field.
  6. Assign IP Address by MAC Address and fill in the field.
  7. Click Next.
  8. You may add DHCP options at the bottom of this screen.
  9. Click Next.
  10. The Dept shortcode field is required and you may add additional Attributes on this screen.
  11. Select the down arrow next to the Save button and select Save & Edit.
  12. On the Edit page, select the DDNS section on the left hand side.
  13. Overide and Enable DDNS Updates by checking the box.
  14. Override and populate your subdomain (domain.buffalo.edu) in the DDNS Domain Name field.
  15. Click Save & Close.

The DNS/DHCP cluster will refresh once every 15 minutes, after which your host will be able to pull a DHCP address from the registered range.

Creating a Static Host Entry

  1. Navigate to the Data Management Tab and then select the IPAM sub-tab.
  2. Navigate to the subnet on which you want to deploy the host and select it.
  3. Select the dropdown menu next to the Add button on the left-hand side.
  4. Select Host.
  5. Select the correct domain using the Select Zone button.
  6. Fill in the Name field with the desired hostname (not the FQDN!).
  7. Make sure the Enable in DNS checkbox is selected.
  8. Add an IP Address by selecting the menu next to the plus symbol. You can also select Next Available and it will auto-populate with the next available IP in your range.
  9. Optionally, fill in the MAC Address and click the DHCP checkbox. This will allow your host to be configured for DHCP and receive a guaranteed static address every time it boots. We don't recommend this configuration for most devices, but it can be useful for printers and dumb devices that cannot be statically configured.
  10. Click Next.
  11. You can add additional Attributes on the next screen.
  12. Click Save & Close.

You can immediately configure your static host once the reservation is saved. If you are using the static DHCP option, you will have to wait 15 minutes for the DHCP address to be available.

Searching for Existing Hosts

  1. Search or filter:
    • Open the search box in the upper right hand corner of the screen by selecting the magnifying glass. The search is robust enough that it will find any host using hostname, MAC address, or IP address.
    • Alternately, you can use the filters below. Select the + (Plus) button to add more than one filter.
  2. Click Search.

Modifying Existing Hosts

  1. Search for the host (see procedure above).
  2. Select the checkbox next to the host and click the Edit icon on the top left of the table.
  3. Modify the record.
  4. Click Save & Close.

Adding/Modifying DHCP Options

  1. Navigate to the host record using the procedure described for the type of host.
  2. Select the checkbox next to the host and click the Edit icon on the top left of the table.
  3. Select DHCP in the left sidebar.
  4. Scroll down to the Custom DHCP Options section.
  5. Select the option and fill in the value, click the + (Plus) button.
  6. Repeat until you've configured all options.
  7. Click Save & Close.

Deleting Existing Entries

  1. Navigate to the host record using the procedure described for the type of host.
  2. Select the checkbox next to the host and click the Delete icon on the top left of the table.

Finding Answers

Please give me access privileges to register and edit my department's DHCP client records.

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.

Who manages DHCP registration?

All the distributed support nodes at UB have the ability to register DHCP hosts for their school or department.  Faculty/staff that need to have their machines registered for DHCP should contact their local IT support node.

DHCP suddenly stopped working on one of my hosts. Things were working fine, I didn't do anything to change the host's DHCP configuration, then for no apparent reason I got an error message that the DHCP client could not obtain an IP address.

DHCP client could not obtain IP address

Click image to enlarge

There are a few reasons you may be getting this issue:

  1. 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. Use the search to locate the host and confirm that it is registered.
  2. The local DHCP Relay agent may be down or experiencing issues. If more than a single host is seeing this problem, report a network problem immediately.
  3. If the machine has had any hardware swapped out recently, you’ll need to update the MAC Address in the host record in the IPAM system. Use the search to confirm that the registered MAC address matches the MAC address on the machine.
  4.  Check the cable and network port by testing them with a known-working machine. If both machines don’t work, swap the cable. If the problem persists, please log a network problem and report a bad port.

How do I release or renew my DHCP IP address?

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