Droms R. The DHCP handbook
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Example 3.7
Example 3.7 configures all five subnets, which involves going through the scope
configuration process, described in the preceding eight examples, once for each
subnet. This appendix doesn’t walk you through that entire process; you should just
repeat the instructions given in the preceding examples once for each subnet to fully
implement the configuration shown in Example 3.7.
Examples 3.8 and 3.9
The Microsoft DHCP server enables you to set a per-scope maximum lease time, but
it does not enable you to set a different default lease time. If a client does not specify
a lease time, it receives the maximum lease time.
The maximum lease time is set in the New Scope Wizard or the Scope Properties
dialog box. The Microsoft DHCP server requires you to set the maximum lease dura-
tion for a scope by specifying the number of days, hours, and minutes, rather than
just adding it all up and specifying a number of seconds. The 10,368,000-second
max-lease-time value in Example 3.9 represents a 120-day lease. The maximum
lease time is initially set in the Set Lease window in the New Scope Wizard. To
change the maximum lease time for a scope, highlight the scope in the DHCP
Manager window and select Action, Properties. Enter the new lease time in the
dialog box, as shown in Figure A.4
APPENDIX A Microsoft DHCP Server Examples446
FIGURE A.4 Setting the maximum lease duration in the Scope Properties window.
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Example 3.9 extends Example 3.7 to include lease duration information, as shown in
Example 3.8.
Example 3.10
Example 3.10 is essentially the same as Example 3.5.
Example 3.11
Example 3.11 shows Example 3.9, with the addition of some global options, as well
as global values for the default and maximum lease times. You cannot set a global
value for the default and maximum lease times in the Microsoft DHCP server.
To define global options, highlight Server Options in the DHCP Manager window
and select Action, Configure Options. The Server Options dialog box appears. Click
DNS Domain Name and enter a value for the option, as shown in Figure A.5.
Example 3.11 447
FIGURE A.5 Entering a domain name in the DHCP Options: Global dialog box.
As mentioned in the section “Examples 3.5 and 3.6,” earlier in this appendix, the
domain-name-servers option corresponds to the Microsoft DNS Servers option. To
set a global value for this option, use the Server Options dialog box described previ-
ously. This option takes an array of IP addresses, similar to the
Router option shown
in the section “Examples 3.5 and 3.6,” earlier in this appendix.
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Examples 12.1 and 12.2
The Microsoft DHCP server doesn’t support multiple address allocation pools or
access control on pools. Therefore, no Microsoft equivalent exists for these examples.
Example 13.1
Chapter 13 provides examples in both Microsoft and ISC forms. Therefore, an
example is not provided in the Microsoft form here.
Examples 14.1 through 14.6
These examples show output of the ISC DHCP server; no equivalent exists for the
Microsoft server.
Example 14.7
The Microsoft DHCP server does not provide equivalents for the default-lease-
time, min-lease-time, allow-bootp, and authoritative parameters. The text in this
appendix for Example 3.9 explains how to set a maximum lease time.
Example 14.8
Example 3.11 shows how to configure values for options to be returned to clients.
Example 14.9
To configure BOOTP file information, highlight the server name in the DHCP
Manager window and select Action, Properties. Then click the Show the BOOTP
Table Folder button.
APPENDIX A Microsoft DHCP Server Examples448
FIGURE A.6 The BOOTP Table dialog box.
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Examples 14.10 and 14.11
The section “Defining New Options” in Chapter 13 describes how to define new
options in the Microsoft DHCP server.
Example 14.12
No known equivalent exists for the Microsoft DHCP server.
Example 14.13
The section “Examples 3.1, 3.2, 3.3, and 3.4,” earlier in this appendix, provides an
example of how to define a subnet for the Microsoft DHCP server.
Example 14.14
Although the ISC server has a general notion of scopes, the Microsoft DHCP server
does not. Instead, it defines three specific scopes—the global scope, the subnet scope,
and the reservation scope. However, Microsoft does not refer to these as scopes;
Microsoft uses the term scope to refer to an IP subnet. The explanation in the section
“Examples 3.5 and 3.6,” earlier in this appendix, shows how to define an option in
the subnet scope. The section “Example 3.11,” earlier in this appendix, shows how to
define an option in the global scope.
To define an option that’s specific to a reservation, select the scope in which the
reservation appears in the DHCP Manager window, and then select Reservations.
Select the reservation you want to modify, and then select Action, Configure
Options. Then enter any options the same way you do in the Reservation Options
dialog box. The sections “Examples 3.5 and 3.6” and “Example 3.11,” earlier in this
appendix, describe how to do this. Figure A.7 shows the Reservation Options dialog
box for a reservation.
Examples 14.15 through 14.17
These examples show Unix-specific Bourne Shell scripts that are used to start the ISC
DHCP server and relay agent, so no equivalent exists for the Microsoft server.
Examples 15.1 and 15.2
See the section “Examples 3.1, 3.2, 3.3, and 3.4,” earlier in this appendix, for the
Microsoft DHCP equivalents.
Examples 15.1 and 53.2 449
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FIGURE A.7 The dialog boxes that are navigated when setting reservation-specific
options.
Examples 15.3 through 15.7
See the sections “Examples 3.5 and 3.6” and “Example 3.7,” earlier in this appendix,
for the Microsoft DHCP equivalents.
Example 15.8
The Microsoft DHCP relay agent is configured by using the Routing and Remote
Access Control Panel. To open the DHCP Relay Agent dialog box, first open the
Control Panel, and then select IP Routing and then DHCP Relay Agent; then select
Action, Properties.
From the DHCP Relay Agent dialog box, you can add a DHCP server by typing in its
IP address and clicking the Add button. Figures A.8 and A.9 show these two dialog
boxes.
You can also configure the Microsoft DHCP relay agent not to relay DHCP packets
until a certain number of seconds has passed since the client started trying to
acquire an IP address. You can also limit the number of hops a DHCP packet can
make before the relay agent discards it. Every time a client request is relayed through
a relay agent, the hop count is incremented by one. When this number reaches the
number you choose in the TCP/IP Properties dialog box, the relay agent does not
relay the packet. In practice, it is rarely useful to relay DHCP packets more than
once, so you should set this number to
1.
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FIGURE A.9 The Windows 2000 DHCP Relay Agent dialog box.
After you have configured the DHCP Relay Agent, right-click the entry in the
Interface window. The dialog box that is displayed allows you to set both the
number of seconds to wait before relaying a client message and the upper limit on
the hop count in a client message. Figure A.9 shows the dialog box for these settings.
Example 15.7 451
FIGURE A.8 The TCP/IP Properties Agent dialog box.
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Example 15.9
This example is specific to Cisco devices. No Microsoft equivalent exists.
Example 15.10
See the section “Example 3.11,” earlier in this appendix, for details about setting up
global options. The
ntp-servers option is equivalent to the Microsoft DHCP server’s
NTP Servers option.
Examples 15.11 and 15.12
See the section “Examples 3.5 and 3.6,” earlier in this appendix, for an explanation
of configuring options for a scope.
Example 15.13
This example is specific to a Cisco router, so no Microsoft equivalent exists.
Example 15.14
The section “Example 3.11,” earlier in this appendix, gives an explanation of config-
uring global and scope options.
Example 15.15
Section 13.3.2 discusses superscopes and explains how to implement the equivalent
of what is shown in Example 15.14.
Example 15.16
The Microsoft DHCP server does not provide a way to define options that apply to a
superscope.
Example 15.17
No known equivalent method exists for doing this with the Microsoft DHCP server.
Example 15.18
See the section “Examples 3.5 and 3.6,” earlier in this appendix, for an explanation
of configuring options.
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Example 15.19
No known equivalent exists for the Microsoft DHCP server.
Example 16.1 and 16.2
DHCP client identifiers are entered through the DHCP Manager by selecting reserva-
tions in the appropriate scope and clicking Add. You must enter client identifiers in
hexadecimal, so it’s not easy to enter an ASCII identifier, as in Example 16.2. Figure
A.10 shows a new reservation added with the same client identifier shown in
Example 16.1. Note the difference in the way identifiers are entered; the ISC DHCP
server expects the numbers to be entered as a sequence of byte values separated by
colons, whereas the Microsoft server expects a sequence of two-digit hexadecimal
values with no separator.
Example 16.4 453
FIGURE A.10 Entering a unique identifier in the New Reservation dialog box.
Example 16.3
You cannot enter a client’s link-layer address as a separate entity from the client
identifier in the Microsoft DHCP server.
Example 16.4
No known equivalent exists for specifying the client identifier sent by the Microsoft
DHCP client.
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Example 16.5
As mentioned previously, you cannot enter a text client identifier.
NOTE
Examples 16.1 through 16.5 assume that it’s possible to talk about client identification sepa-
rately from static IP address assignment, but this is not possible with the Microsoft DHCP
server. That is why the New Reservation dialog box shown in Figure A.10 has a space to enter
an IP address.
Example 16.6
This example shows a configuration that includes global options, a subnet declara-
tion with subnet options, and two static IP address assignments. See the section
“Examples 3.5 and 3.6,” earlier in this appendix, for information on how to define
global options.
The explanation in the section “Examples 3.1, 3.2, 3.3, and 3.4,” earlier in this
appendix, shows how to create a new scope, which is equivalent to a subnet declara-
tion. The Microsoft DHCP server requires that reservations be allocated from the set
of addresses that are available within the scope. To define a subnet as shown in
Example 16.6, you create the scope by using the New Scope Wizard as described in
the section “Examples 3.1, 3.2, 3.3, and 3.4,” earlier in this appendix, and include
the addresses for the two static assignments in the scope. Then you exclude the IP
addresses for the static assignments by entering exclusion ranges. Figure A.11 shows
the subnet in Example 16.6 being added, adding the exclusion range for the two
static assignments.
APPENDIX A Microsoft DHCP Server Examples454
FIGURE A.11 Excluding addresses from the dynamic address pool.
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To add the reservations for the two servers, select the new scope in the DHCP
Manager window, select Reservations in the scope, and then select
Action, New
Reservation. Figure A.12 shows the host dns-server.genericstartup.com being
added, using the
New Reservation dialog box. This dialog box enables you to enter
more than one client; after you click
Add, the dialog box is cleared so that you can
enter a new static IP address assignment.
Examples 16.10, 16.11, and 16.12 455
FIGURE A.12 Adding a reservation for the GSI DNS server.
Examples 16.7 and 16.8
To find a client’s lease information in the Microsoft DHCP server’s lease database,
you must know in which scope the DHCP client obtained its IP address. The easiest
thing to do is to examine the client’s configuration information to find out what IP
address it was assigned. Select the scope containing that IP address in the DHCP
Manager window, and select Address Leases. The Address Leases window displays all
the active leases in that scope, as shown in Figure A.13.
Examples 16.9, 16.10, and 16.11
No known equivalent exists for the Microsoft DHCP server.
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