DHCP 配置说明
DHCPv4 Service Option Description
Default Lease Time Specifies the default lease time that will be offered to DHCP clients.
Maximum Lease Time Specifies the longest
possible lease time that
will be granted to a DHCP
client.
Minimum Lease Time Specifies the shortest
possible lease time that
will be granted to a DHCP
client.
Client Updates Indicates whether client
updates should be used to
maintain DDNS records for
this client. When selected,
the client updates its own
DNS record on the server.
When not selected, the DHCP
server performs the update.
This option is required for
DHCP to perform DDNS
updates.
DDNS Domain Name Specifies the domain name
appended to this client’s
hostname to form the fully-
qualified DNS name that will
be dynamically updated by
the DHCP server.
Specifies the hostname that
should be used for DDNS
updates for this client. If
no value is specified, the
hostname provided by the
DHCP client will be used. In
the General section, define
the following parameters:
Type—select the type to be
used as part of a DDNS
hostname value: IP Address
or MAC Address.
Position—specify where you
wish to add the data value
to the IP address or MAC
address to create the DDNS
hostname. Select Prepend to
add the data value specified
in the Data field in front
of the IP address or MAC
address. Select Append to
add the data value specified
in the Data field at the end
of the IP address or MAC
address.
DDNS Host Name
Data—specify data value
that will be used to be
prepended or appended to the
IP address or MAC address to
form the DDNS hostname. DDNS Reverse Domain Name Specifies the domain name
appended to the client's
(reversed) IP address to
form the fully-qualified
reverse DNS name. By
default, this value is in-
addr.arpa.
DDNS TTL Specifies the default TTL
for DDNS records, specified
as an integer value from 0
to 4,294,967,295 seconds.
The values can be set in
seconds, minutes, hours or
days.
DDNS Updates
Indicates whether the server
should attempt a DDNS update
when the lease is
acknowledged by the DHCP
client. When the Enabled
check box is selected, the
DHCP server updates DNS
records on the DNS server.
NOTE: DDNS Updates are
enabled by default in
Proteus and this can cause a
slow or unresponsive DHCP
service because the DHCP
service runs in a single
thread leading all DHCP
lease updates are processed
serially. In order to avoid
this issue, disable DDNS
Updates manually.
Ping Check Indicates whether the server
should use an ICMP “ping”
to ensure that only inactive
IP addresses are offered to
DHCP clients. By default,
Ping Check is globally
enabled.
Always Broadcast Sets the server to always
broadcast its responses to
compensate for some clients
that would not otherwise
receive responses.
Always Reply (RFC 1048)Indicates that the server
should always reply with RFC
1048-style responses. This
is true even if clients do
not make RFC 1048-style
requests.
Dynamic BOOTP Lease Length Indicates the lease length
after which a BOOTP client
is assumed to be offline.
Specified as an integer
value between 0 to
4,294,967,295 seconds. The
values can be set in
seconds, minutes, hours or
days.
File Name The name of the initial boot
file which is to be loaded
by a client. Boot files are
generally made available to
clients by TFTP.
Get Lease Hostnames When selected, the server
looks up the domain name for
each client and uses the
information from the zone to
set the hostname option for
the client.
Minimum Seconds Specifies the amount of time
that the DHCP server waits
before responding to client
requests. A setting of 1
always results in the second
request being answered
rather than the first. This
is useful for setting up a
secondary DHCP server that
allows the primary to
respond to the first
request. Specified as an
integer from 0 to 255.
Next Server Specifies the server where
the boot file is located. Server Identifier Overrides the value that is
sent to clients in the DHCP
Server Identifier option.
This must be a valid IP
address already assigned to
the DHCP server. This value
is usually set
automatically; using this
option is not recommended.
Site Option Space Sets the site option space
for a given DHCP scope. This
option is only useful in
combination with deployment
of an option space
definition in a DHCP Raw
option.
Stash Agent Options This checkbox causes the
client to include the DHCP
agent information from the
initial DHCPREQUEST message
in all subsequent messages. Update Optimization When selected, the DHCP
server only attempts a DDNS
update if it appears that
client information has
changed, rather than every
time the client’s lease is
renewed.
Update Static Leases When enabled, the DHCP
server will also perform
DDNS updates for static
(DHCP Reserved) leases.
Use Lease for Default Route When selected, the client’s
own IP address is sent as
the router address rather
than the actual address of
the gateway. This can make
some Windows clients ARP for
all IP addresses if the
router is set up for proxy
ARP.
One Lease Per Client When selected, the server
clears all existing leases
for a client upon the
receipt of a new DHCPREQUEST
message. This ensures that
an interface obtains only
one lease at a time for a
segment.
Allow MAC Pools Allows the selected MAC Pool
access to DHCP services.
After this option is set,
MAC addresses not belonging
to the selected MAC Pool are
automatically denied.
Multiple instances of this
option may be added, to
allow DHCP service to
members of multiple MAC
Pools.
Deny MAC Pools Denies DHCP services to the
specified MAC Pool wherever
it is active. DHCP
reservations take precedence
over this option.
Deny Unknown MAC Addresses Denies unknown MAC Addresses
from using DHCP services
wherever it is active.
Allow Class Members of Allows DHCP clients who
match a specific class value
to receive an IP address at
the level the option is set.
This option also denies all
non-matching hosts from
receiving an IP address. One
or more DHCP match classes
must be created before
setting this option. For
more information about
adding and editing DHCP
Match classes, refer to DHCP
Match Classes.
Deny Class Members of Denies members of DHCP
clients who match a specific
class from receiving an IP
address at the level the
option is set. All clients
who do not match this class
value are able to receive an
IP address. One or more DHCP
match classes must be
created before setting this
option. For more information
about adding and editing
DHCP Match classes, refer to
DHCP Match Classes. DHCP
reservations take precedence
over the specified by this
option.
Conflict Detection Proteus DDW Only: Instructs
a Windows DHCP server to
ping the IP address it is
about to assign to determine
if the address is already in
use. This helps to prevent
duplicate IP addresses on
the network. From the
Retries list, select a value
from 0 to 5.
Update Conflict Detection When enabled, the server
used in combination with
DDNS updates to enforce
ownership of a DNS name.
When this option is enabled
and the DHCP server performs
a DDNS update for the
client, an additional TXT
record will be added to DNS
to record the DHCID of the
client that owns this DNS
entry. Other clients will
not be allowed to update or
remove this DNS entry by
DHCP, even if they have the
same hostname. This option
is enabled by default.
Do Reverse Updates
Controls whether or not DHCP
performs reverse DNS updates
for clients. When this
option is not present,
servers perform reverse
updates by default. Use this
option when you want to
disable reverse updates.
When this option is present
and the Enabled checkbox is
selected, the selected
server performs reverse
updates. This is the
equivalent of this option
not being present.
When this option is present
and the Enabled checkbox is
not selected, the selected
server does not perform
reverse updates.