Use the IP Ranges parameters to specify the IP addresses available for assignment to clients.

To configure the server IP ranges:

1. Choose the Server/Security tab.
2. Choose a server from the server list.
3. Choose IP Ranges from the drop-down list.
4. Choose [New IP Range].
5. For each IP range, enter the subnet address or name, a server address, and an IP range to be assigned to clients on the selected subnets.

You can change any or all of the IP range parameters described in this section.

Subnet Address

Enter the subnet address or name.

DHCP Server (address)

Enter the IP address or name of the Server. You can configure more than one DHCP server on a local area network (LAN) or subnet.

IP Ranges

The IP Address Range is a group of unique IP addresses that the server can assign to clients on a selected subnet.

1. Enter the beginning of the IP Address Range for the subnet: network, subnet, and host address.
2. Enter the end of the IP Address Range.
3. If your network has more than one subnet, enter the remaining subnet IP numbers.

Note A subnet address may have more than one corresponding IP Address Range.

The server can configure clients on more than one subnet when the routers between the server and the client forward BOOTP packets.

Use the Hostnames Lists Parameters to configure a host name. If you have set the server configuration so that the server automatically accepts the name a client suggests for itself, you do not need to set up host names.

To configure a host name:

1. Choose the Server/Security tab.
2. Choose a server from the DHCP server list.
3. Choose Hostname Lists from the drop-down list.
4. Choose [New Hostname List].
5. For each host name, enter:
   • Domain name
   • DHCP server name
   • Hostname Prefix (Required as part of the host name.)
   • Host name(s)

You can use the following host name list parameters to set up host names.

Domain Name

Specifies the domain name. Enter the domain name exactly as it was assigned by the NIC Domain Registrar, including its top level domain extension. For example, enter school.edu, company.com, or city.gov.

DHCP Server

Enter the IP address or name of the DHCP server.

Hostname Prefix

Specifies a host name prefix.

The host name prefix is used when a computer requests a host name and one is not available.

Using the mycompany.com domain as an example, assume:

• All names in the host name list have all been assigned.
• Hostname Prefix is magic.

Then, the DHCP server gives the host names magic1 and magic2 to the next two computers that request host names.

Enter a specific host name prefix.

Hostnames

Specifies the list of host names. Enter as many host names as needed. Different DHCP servers can own the same host names.

You can use the Active IP Snapshot window to check the statistics of IP addresses, add a new record, remove a configuration, and import a file into the active IP database.

Checking the Status of a Configuration

The left side of the Active IP Snapshot window lists each configured DHCP client. To see the details of a configuration:

1. Choose the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. Select a record on the left side of the window.
4. Review the information on the right side of the window. The right side of the window lists the information that applies to the selected record configuration.

Adding a New Record

Typically you only add a new record when you intend to permanently attach a hardware address to an IP address. The IP address does not need to come from the DHCP IP addresses you have defined.

Note You must stop the DHCP server before you modify information in the Status Database.

To add a new record:

1. Choose the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. Choose [New Record].
4. Enter a value for each parameter.
5. Click Add.

Changes made to the database take effect immediately.

Note Ensure that the IP address you specify does not belong to any pool of IP addresses configured in an IP Range. If it does, it could be released and used by other clients (MAC address).

Removing a Configuration

To remove a configuration, use the following procedure:

Note You must stop the DHCP server before you modify information in the Status Database.

1. Choose the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. On the left side of the window, select the record you want to remove.
4. Click Delete.

Changes to the database take effect immediately.

Importing a File into the Active IP Database

To import a file into the IP database:

1. Choose the Server/Security tab.
2. Choose Active IP Snapshot from the drop-down list.
3. Click Import.
4. Enter the file name you want to import.
5. Click OK.

Changes to the database take effect immediately.

Note The file being imported must be in ASCII format, and each record in the file must start on a new line. Separate the fields within each record with a vertical bar ( | ).

Refreshing the Active IP Snapshot Window

To refresh the Active IP Snapshot window so that it reflects the current status of the database, click Refresh.

Use the Preload MAC Address window to create a list of hardware (MAC) addresses that are restricted to the server.

Use the Preload MAC Addresses window to restrict assignment of IP addresses. To enable this security measure, set Restrict to known MAC addr to True in the Server/Security Parameters window. You can then manually assign the desired MAC addresses. The server ignores all other client DHCP requests.

Checking the Status of a MAC Address

Each configured MAC address and type is listed on the left side of the Preload MAC Addresses window. To see the details of a MAC address:

1. Choose the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Select a record from the left side of the window.

The right side of the window lists the information applicable to the address.

Adding a New MAC Address

Typically, you add a new MAC address when you want to restrict the server to work with a specific set of MAC addresses.

To add a new MAC address:

1. Choose the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Choose [New Record].
4. Enter a value for each parameter.
5. Click Add.

Changes to the database take effect immediately.

Removing a MAC Address

To remove a MAC address:

1. Choose the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Choose the MAC address you want to delete.
4. Click Delete.

Changes to the database take effect immediately.

Searching for a MAC or IP Address

To search for a MAC or IP address:

1. Choose the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Click Find.
4. Enter the MAC or IP address you want to locate.
5. Click OK.

Importing a File into the MAC Address Database

To import a file into the MAC address database:

1. Choose the Server/Security tab.
2. Choose Preload MAC Addresses from the drop-down list.
3. Click Import.
4. Choose the file to import.
5. Click OK.

Note The file being imported must be in ASCII format, and each record in the file must start on a new line. Separate the fields within each record with a vertical bar ( | ).

Refreshing the MAC Addresses Window

To refresh the MAC address window so that it reflects the current status of the database, click Refresh.

A subnet is a segment of a logical network that has been divided into smaller physical networks. Use a Subnet address when you want to set up a configuration for a group of clients.

Use the Subnets tab of the GUI to enter the necessary information to add and customize subnets to your network. Make all entries at the server computer.

7.8.2.1 Using Subnet Parameters

There are two ways to assign configuration parameters to DHCP clients. You can assign parameters to:

• A specific client
  To assign parameters to a specific client, use the node configuration options described in Section 7.8.3.
• A group of clients
  To assign parameters to a group of clients, use the subnet configuration options described in this chapter.

If you are using standard Class A, B, or C addressing and are not subnetting, group your clients per-network instead of per-subnet. Configure each client within this group with similar parameters, for example, DNS domain name or DNS servers.

7.8.2.2 Configuring a Subnet

You do not have to change every value for the parameters in the GUI Subnets tab. If you want to specifically configure DHCP to use a unique aspect of your network configuration, change only the necessary parameter values to reflect the appropriate network settings.

To configure a subnet using the Subnet Tab of the GUI, use the following procedure. For a description of the subnet parameters, see Section 7.9.

1. Choose the Subnets tab.
2. Choose [New Record].
3. Choose BASIC DHCP Parameters from the drop-down list.
4. Choose the Name parameter from the Name/ID Parameters menu.
5. Enter the name of the subnet configuration in the Value field.
6. Choose the Net or Subnet IP Address. Enter the Net or Subnet IP address that identifies the subnet portion of the network.
7. Choose Host IP Address. Enter the IP address of the host computer.
8. As appropriate, enter information for Network, Lease, Time, BOOTP, NetBIOS, X window, TCP, IP, and Link parameters. For more information about these parameters, refer to Section 7.9.
9. Choose Update from the File menu to update the server with the new configuration.

The new configuration takes effect immediately.

7.8.2.3 Removing a Subnet Record

To remove a subnet record:

1. Choose the Subnets tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose the subnet record you want to delete.
4. Click Delete.

Changes to the database take effect immediately.

7.8.3 Defining Node Parameters

A node is a workstation, computer, or other device on the network. Typically, the settings for a node override a subnet or group setting. Nodes may be a member of a group, and a group can be a member of another group.

Use the Nodes tab of the GUI to enter the information to add and customize nodes on your network. Make all entries at the server computer.

7.8.3.1 Using Node Parameters

You can assign configuration parameters to a group of clients and to individual systems by specifying node parameters. By specifying parameters for a specific MAC-address, you can assign parameters such as DNS domain name or host name to a single system.

7.8.3.2 Configuring a Node

Typically, the settings for a node override a subnet or group setting. Nodes can be a member of a group, and a group can be a member of another group. You need not change every value for the parameters in the Nodes tab. However, to configure your DHCP server to use a specific unique aspect of your network configuration, you need to change the parameter values to reflect the appropriate network settings.

To configure a node using the Node Tab, use the following procedure. For a description of the node parameters, see Section 7.9.

1. Choose the Nodes tab.
2. Choose [New Record].
3. Choose Name. Enter the name of the node configuration.
4. Select Hardware Type. Enter the type of network the node is connected to; for example, Token Ring, Ether3, Pronet, Arcnet, or 0 (see Table 7-3).
5. Select Hardware Address. Enter either the hardware address or the client ID of the node.
   If the Hardware Type defined in step 4 is 0, enter the Client ID (an alphanumeric string that you define).
   If you are using the hardware address (MAC address) of the node, enter it using the format xx:xx:xx:xx:xx:xx, for example, 00:00:90:75:31:81. The hardware address is assigned during manufacturing, and usually appears when you turn on or reboot your computer.
6. Select Member of Group. Enter the name of the group the node is joining.
7. Select Host IP Address. Enter the IP address of the host computer.
8. Enter information for Network, Lease, Time, BOOTP, NetBIOS, X window, TCP, IP, and Link parameters. For more information about these parameters, see Section 7.9.
9. Choose Update from the File menu. This updates the server, allowing the new configuration to take effect.

The new configuration takes effect immediately.

Table 7-3 Network Type Symbol and Number

Symbol	Number	Network Type
ethernet or ether	1	10 Mb Ethernet
ethernet3 or ether3	2	3 Mb experimental
ax.25	3	AX.25 Amateur Radio
protnet	4	Protnet proNET Token Ring
chaos	5	Chaos
token-ring,tr,ieee802	6	IEEE802
arcnet	7	ARCnet

7.8.3.3 Removing a Node Record

To remove a node record:

1. Choose the Node tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose the Node record you want to delete.
4. Click Delete.

Changes take effect immediately.

7.8.4 Group Parameters

A group is a collection of workstations or other computers on the network that share a common configuration. Assigning workstations to groups from the server computer makes it possible to quickly implement a hierarchy of available network services across many clients.

7.8.4.1 Using Group Parameters

You can define a group so that a set of workstations on one subnet has the same configuration values. Once you define a group of settings for one MAC address or subnet number, you can use those settings for other node or subnet configurations.

For example, you might want one group to include specific lease time information for your network environment. The next time you configure a computer, you can use that group as the basis for the configuration.

7.8.4.2 Defining a Group

To define a group using the Group Tab, use the following procedure. For a description of the group parameters, see Section 7.9.

1. Choose the Groups tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose [New Record].
4. Choose the Name parameter. Enter a name for this group configuration.
5. Choose Member of Group. If appropriate, enter the name of the group to which the new group will belong.
6. Choose Host IP Address, then enter the IP address for the host computer.
7. Choose Group Members. Enter the names of subnets, nodes, or other groups that are to be a member of the group.
8. Enter information for Network, Lease, Time, BOOTP, NetBIOS, X Window, TCP, IP, and Link parameters as appropriate. For detailed information about these parameters, see Section 7.9.
9. Choose Update from the File menu.

The new configuration takes effect immediately.

7.8.4.3 Removing a Group Record

To remove a group record:

1. Choose the Group tab.
2. Choose DHCP Parameters from the drop-down list.
3. Choose the Group record you want to delete.
4. Click Delete.

Changes to the database take effect immediately.

7.8.5 Defining Systemwide Logical Names

You define systemwide TCPIP$DHCP logical names in the SYS$STARTUP:TCPIP$SYSTARTUP_VMS.COM file. After making changes to the file, restart the DHCP server for the changes to take effect.

You can modify the following DHCP server characteristics:

• The directory location where the DHCP configuration files and databases are placed during TCPIP$CONFIG
• Error logging and diagnostics
• The time allowed before the DHCP server process times out because of inactivity

Table 7-4 outlines the DHCP logical names, default settings, and characteristic options.

Table 7-4 DHCP Server Logical Names

Logical Name	Characteristic
TCPIP$DHCP_CONFIG directory	If defined, places the following DHCP files (during TCPIP$CONFIG) in the directory you specify: DHCP configuration files in ASCII format (for example, SERVER.PCY) DHCP database files in binary format (for example, DBA.BTR) Binary database lock files (for example, RWLOCKDBA.) Temporary files created by TCPIP$CONFIG during the BOOTP-to-DHCP rollover The server's process identification file (JOIN.PID) Useful when you want to move the file location off the system disk or when you want to set up a DHCP cluster failover environment (see Section 7.5). Must be defined before running TCPIP$CONFIG. If not defined, the above DHCP-related files are placed in SYS$SYSDEVICE:[TCPIP$DHCP] during the TCPIP$CONFIG procedure.
TCPIP$DHCP_DEBUG value	Logs full diagnostics. Valid numeric values are 1 through 6.
TCPIP$DHCP_LOG_LEVEL value	Writes the specified level of diagnostic information to the log file. Ignored if TCPIP$DHCP_DEBUG is defined. Valid numeric values are: 0 No logging. Default. 1 Warning messages logged. 2 Log all messages.
TCPIP$DHCP_IDLE_TIMEOUT value	If defined, the DHCP server process exits after the number of minutes of inactivity you specify. If not defined, the DHCP server process (once started) does not exit until you disable or shut down the process.
TCPIP$DHCP_LOG name	Defines the name of the DHCP server log file. Default: TCPIP$DHCP_RUN.LOG. If defined, each time the auxiliary server starts a DHCP server process, two log files are created: the one you define with TCPIP$DHCP_LOG name and the default TCPIP$DHCP_RUN.LOG. If an existing version of the file defined with TCPIP$DHCP_LOG exists, DHCP uses that version and appends any new lines.

7.9 Parameter Descriptions for the DHCP GUI

This section describes the subnet, group, and node parameters. The parameters are grouped by the following categories:

• Name/ID Parameters
• Key Parameters
• BOOTP Parameters
• IP Parameters
• Lease Parameters
• Link Parameters
• NetBIOS Parameters
• Network Parameters
• TCP Parameters
• Time Parameters
• X Window Parameters

For any parameter, list the values in order of preference.

7.9.1 Name/ID Parameters

Name and identification parameters determine the name of the configuration and information that identifies which client or clients are being configured by this record.

Name

Specifies the name for this subnet, node, or group configuration.

Group Members

Specifies the names of subnets, nodes, or other groups the member is joining.

Member of Group

Specifies the name of the group the new subnet, node, or group is joining.