The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol. DHCP allows for computers to be configured automatically to communicate with each other over an IP network without the need for manual setup by a network administrator. The implementation of DHCP relies on a DHCP server to hand out network configuration information to DHCP-capable clients that request an IP address (and other information required or useful in communicating with other devices on an IP network). In addition to an IP address, common configuration information served over DHCP includes a default gateway, subnet mask and DNS sever(s).

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I have a Server running Server 2008 R2 Standard and a Sonicwall TZ500. I setup a DHCP Scope on the server to be - 100 and on the Sonicwall - 254. The problem im having is that the server will run out of IPs and the Sonicwall wont take over. Im not sure if i need to enable IP helper on the sonicwall. Does anyone have experience with this type of setup.
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I have just installed a new network with one server, configured as a domain controller running Windows Server 2019 and about 10 workstations running either Windows 10 or Windows 7.  This is something that I have done successfully numerous times.  However, this one is causing me problems as computers are not getting IP addresses or DNS from the DHCP server and even when they are given static IP and DNS, they do not get Group Policies, for example, mapped drives or folder redirection.  Even those PC’s that have been given static IP and DNS still can’t reach every web site, including their own. Roaming Profiles do appear to be working.
On one PC that was showing an IP that may have been setup statically by the owner (who was away so I couldn’t ask him) I flushed the DNS and released the IP address and re-booted the computer.  It failed to get any IP.

There was a previous server that was in use prior to the company moving to new premises and we were instructed to use the same domain name.  Each workstation was taken off the domain by making it join a Workgroup and was then joined to the new domain (of the same name).  However, this was only possible with static IP, etc.  All the workstations are now members of the new domain.

The old server had started to develop problems before the office move and is inaccessible.

Server has a static IP:
Default Gateway (the router):

DHCP has been setup with a scope of – …
I upgraded a 2008 R2 Datacenter server functioning as a domain controller and DHCP server. I upgraded to 2012 R2 Datacenter. I made it a replica domain controller with DNS and made it a Global Catalogue server and then installed the DHCP server role. I backed up the DHCP database on the 2008 server, copied the file to the new 2012 server and I believe I successfully imported the dhcp database file. I have done this many times. All the scope settings, reservations, lease, etc. showed.
I went to authorize the new server and it says it’s authorized under manage authorized servers but will not issue IP addresses.
When I select IPv4 or Scope within the console, it says the server needs to be authorized.
I have installed and uninstalled everything several times but end up with the same result = no ips being issued.
Suggestions please ????
My DHCP server tree does not expand.  See screenshot.  I have been having an issue adding a static ip address to a computer as well.  Any ideas for this issue?  It has never done this since I set it up 6 years ago.    Windows Server 2008 R2
Not sure what I'm doing wrong in trying to setup an ip address on a win 7 pro laptop.  I am trying to change the ipv4 settings from "obatain auto" to an ip address I specify.  I have done this before and it has worked.  When I enter the info and exit it says that DHCP is not enabled and then the settings go back to auto obtain.  Any ideas?
I had this question after viewing Can Ping Gateway but NOT DNS Server.

A client of mine has this same issue. The fix in "Can Ping Gateway but NOT DNS Server" did not work. I have applied all of the fix items noted in that thread, including the fix solution.

Some data:

Four computers in this office are just fine. They can ping the gateway located at They can ping the DHCP Server located at They can ping the DHS Server located at I have attached the results of an ipconfig /all command here as the file ipconfig.good.txt.

One computer is having problems. It can ping the gateway at, but CANNOT ping the DHCP Server and DNS Server at I have attached the results of an ipconfig /all command here as the file ipconfig.bad.txt

The problem happened out of the blue yesterday afternoon. The Windows error logs show no suspicious events during that time period. The machine has a clean registry and clean malware status.

All ideas invited.

-- stan

- - - - - -
Stanley Krute
Chief Technologist
Siskiyou Digital Inc.

I have a WDS set up on my network.
It is not on the same server as the DHCP.

I am not seeing option 60 appearing in my DHCP scope options.
Also, how do i get WDS to be discoverable across multiple subnets?
Is there anything for my network team to configure?
We already have ip helper-address configured to point the different subnets to the DHCP server.

I just want to clarify something about scavenging and dhcp lease time. Does the scavenging Refresh and No Refresh settings have to be equal/or less than the dhcp lease time or does the scavenging period have to be equal/or less to the dhcp lease time? For example if my dhcp lease time is 4 days then should refresh and no refresh period be at most two days a piece? What should the scavenging period be for this amount of time, does it matter?

Thank you.
I am implementing an Aironet deployment, and I am not sure if I am seeing unnatural instability... or if these things just "do" this sort of thing. My infrastructure is solid, and I am using two subnets- and My wireless devices will all exist on the subnet, so the access points are plugged in there, and I have also connected two of the ports on the WLC 3504 to the subnet. I have also connected the service port on our subnet, for a number of reasons I won't go into now. There is no DHCP server on the subnet, but there is one on, and the subnets are physically connected via Cisco 2901 router. The service port is configured at and the two other ports are statically set and Just letting things sit, I noticed the SSID's keep appearing and disappearing every few minutes and I consoled in to the AP to see this cycle:

[*08/13/2019 18:50:24.7198] AP has joined controller USMDWLC00
[*08/13/2019 18:50:24.7698] DOT11_DRV[0]: Stop Radio0
[*08/13/2019 18:50:24.7798] DOT11_DRV[0]: Start Radio0
[*08/13/2019 18:50:25.9294] DOT11_DRV[1]: Stop Radio1
[*08/13/2019 18:50:25.9394] DOT11_DRV[1]: Start Radio1
[*08/13/2019 18:50:27.3889] Password for user changed
[*08/13/2019 18:50:27.5989] save_on_failure is set to 1
[*08/13/2019 18:50:27.5989] save_on_failure is set to 1
[*08/13/2019 18:52:08.6904] Re-Tx Count=1, Max Re-Tx Value=5, …
Current Configuration:

Three DCs:
DC01 Running Server 2016 Standard, running AD, DNS, WINS
DC02 running Server 2012 R2, running AD, DNS, WINS and DHCP fail-over from DC03.
DC03 running Server 2012 R2, running AD, DNS, WINS, and DHCP with fail-over to DC02, and all FSMO roles
NAS containing User's Data and Roaming Profiles, redirected via GPO's. Some Public data is stored on DC01.
33 Users
4 User PC's - All users are required to have access all four PC's (hot desking).

All replication works fine for AD, DNS and WINS, as does the DHCP fail-over.

I need to update the whole network to native Windows Server 2016 Standard, or better still 2019, without turning the above servers into doorstops, and with the minimum of downtime.
At the end of this exercise, DC02 will be removed from the network completely, as it is not upgradeable, and will only run 2012 R2.
DC03 will also be removed from the network, but will have the Motherboard upgraded, and the system rebuilt as Server 2016 Standard or preferably 2019 Standard.

Can I do it like this?

01 Move all of the FSMO rolls from DC03 to DC01. This would make DC01 the Primary controller.
02 Remove DHCP from DC02 and DC03, and put it on DC01. Break the fail-over between the DC01 and DC02, and then add the DHCP role to DC01. Finally, do backup of DHCP from DC03, and then restore on to DC01.
03 Remove DNS, and WINS from servers DC02 and DC03, leaving DC01 as the only server running DNS and WINS.
04 Demote DC02 and …
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We have two Cisco 5508X firewalls (one is for failover).  For VPN, we use the old Cisco VPN Client (5.7) and IPSEC.  In the configuration of the firewall, clients authenticate against the domain controller’s address.  The domain controller’s OS is MS Server 2016 Datacenter.

We have noticed in DNS (Microsoft) that some of the VPN clients have the same IP addresses.  There is not a DHCP scope (Microsoft) setup for the VPN network.  To ensure that each VPN client has a separate IP address, can I simply create the scope in DHCP (Microsoft), or is there more to it?
Have an HP Color LaserJet CP4025.

Believe the NIC card is bad but have not proven it to my complete satisfaction.

As I am nervous Ned, I want to be sure before the boss brings in the Printer Guy at $150 an hour and proves me the fool.

Printer lost connectivity to the switch.

Checked all the patch cables from the printer, through the wall, to the switch.

All good.

Checked the config on the switch.

All good.

Used other ports on the switch.

All good.

Still no connectivity.

Tried to connect an RJ45 cable from a computer NIC to the printer NIC.

The printer does not show any default 169 do IP address.

The JetDirect menu choice from the printer display is missing meaning I cannot set DHCP.

Did a factory reset.

Did a cold reset.

No go.

Should I grab a laptop and a serial cable and give it a go, or has Nervious Ned done everything he can do to prove the NIC is bad?
I need to add Option 66 to DHCP Server on FortiWiFi 61E Firewall.  I don't have that listed under "Additional DHCP Options".  Is it possible to do?
I have a windows 2000 R2 standard AD server which is doing DHCP. When a look at my leases I have a lot of "BAD ADDRESS IP IN USE". The clients are set for DHCP. The DHCP server is not keeping track of IP addresses leased. What could be causing this. Causing headaches.
I installed a new Cisco smart switch and the system light is solid, meaning it is using DHCP.  How do I find the IP?
Hello IT gurus

I have microsoft windows DHCP, DNS, and Active Directory servers in the clouds. but now I'm migrating them to newly built datacenter. I need to export them, or their database, and their settings to the new servers in the new datacenter.

Is that possible?
if it's yes, how?

I have pc which has his IP reserved in DHCP server. The DHCP is configured to update DNS.

Now if I deleted the PC  A record name in DNS. When DHCP will recreate it in DNS?
We have multiple sites all on different subnets, we have one central DHCP server which I want to change (so I can do maintenance).

I want to add a second DHCP server (for redundancy) but I can only broadcast one helper address from the site routers.  I have read up on virtual IP's but am unsure if this is the correct way to go.

We have multiple DC's in different geographical locations
Routers are part of our MPLS so I cannot make changes (I can have the helper add changed)
All servers are in the hosted data center (VM's)

All help/advice gratefully received.
I am trying to add a 2016 standard server as a DC to a 2008 R2 network.  Once it is added, it will become the only Domain controller on the network and the 2008 R2 will be removed.
I have joined the domain, and added Active Directory Domain Services, DHCP Server, DNS Server and the various roles.  When I go to promote the server, I get a " cannot find the domain controller  error and suggests I check the spelling of the domain.
The domain is chosen from the drop down menu, and is correct.
Should I tried to promote it to a domain controller prior to joining the network?
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Last week we were shut down for factory maintenance.  We brought a new primary domain controller on line and demoted the old, and moved DHCP to the new PDC.  Since then our wireless devices have been picking up the wrong address.    For example, wireless devices should pick up an xxx.xxx.133.xxx address, but report they have an xxx.xxx.130.xxx address, and then they do not connect to the network.  We did not have an idea of the full impact, but the wireless network is basically down.  There are a hand- full of devices that have the proper address.  I don’t have a clue where to begin.  Normally, I would check the network switches, and I did briefly.  However, this started when we switched domain controllers.  So, I think it might a better use of time to look at the DHCP side, which I have briefly.  Where and what do you think I should start looking at?
Hello gents I have a new Cisco Aironet Mobility Express 1830 series POE AP connected to a port in my POE switch.   The AP is getting activity as there is currently a solid green light on the device.   I am looking in my DHCP scope and not seeing the unique ID show up for the device so I could locate the IP address.   Anyone know if they can advise if the port on the switch is assigning a dhcp IP to the device from the server since the device is getting activity and how I can see if the device is online other than CDT which is not picking it up
The old saying that "I do not want to start another elephant for just one elephant sandwich applies here. My knowledge of how the internet operates is a 2 on a 1-10 scale . For instance, I have no idea whatsoever what  purpose a subnet mask or a default gateway are for.  I have no idea what a TCP or a UDP port are for. Preferred DNS? Alternate DNS? Not a clue. I choose not to educate myself on these matters because my  interests are intense in other areas and my need for this new knowledge is infrequent. Why the need for a mini article? I am in the midst of installing an NVR and POE switch for a surveillance system for my residence and lab. I have only got eight cameras. Four of them at present are PTZ capable. The difficulty occurs when a camera fails or I wish to change camera models. It is not as simple as plugging in the new POE camera into the POE capable switch. When being helped by someone that knows how to do this they, for a moment turn on DHCP (whatever that is) and obtain different addresses or settings, then turn it off. It comes second nature to those with this knowledge and often takes ony 2 minutes to install any brand of camera  if it has ONVIV compatibility. What would be great is having a mini course or flowchart with which to install a new camera.

Perhaps such a set of "Dummied down" easy instructions already exists. If they do I do not know where they are. For all I know learning all the above may only take a couple hours, but I doubt that it is so …

Currently we are trying to utilize PXE boot across subsets in our environment. Please read below for more information

Current network environment:
●      The USG Router and Switches are assigned static IP addresses listed above
●      The USG router has networks/vlans created on them via the UBNT controller UI (v5.10.23.0)
●      The USG Router is responsible for DHCP for each network
●      Our WDS/MDT server is sitting on vlan 100
●      We are able to PXEboot clients on the same subnet (10.10.1.x/24)
●      Issue: We are trying to have clients on the Techbench network vlan 3340 be able to communicate pxe boot to our wds server (

Current settings in DHCP TechBench4 network
Advanced DHCP Options:
Error on Client machine:
I will soon place wireshark traffic logs when i finish testing:

Two questions:-
1. Is there a way that i can automate the creation of reverse lookup zones when i create a scope in DHCP?
2. I have quite a large number of DHCP scopes created already, for which i have no reverse lookup zones configured. Is there a way that i could automate the creation of these zones in DNS
I'd like to disable netbios

I set
HKLM:SYSTEM\CurrentControlSet\services\NetBT\Parameters\Interfaces\ {GUID OF NIC} \NetbiosOptions = 2

for each NIC on my domain controllers and restarted.

this can also be done by powershell script
$key = "HKLM:SYSTEM\CurrentControlSet\services\NetBT\Parameters\Interfaces"
Get-ChildItem $key |
foreach { Set-ItemProperty -Path "$key\$($_.pschildname)" -Name NetbiosOptions -Value 2 -Verbose}

$key = "HKLM:SYSTEM\CurrentControlSet\services\NetBT\Parameters\Interfaces"

Open in new window

then removed netbios option on DHCP Scopes.

Now I'd like to create a GPO to disable "TCP/IP NetBIOS Helper" service as well as "NetBt" service as a test on some devices according to this

However, only the NetBT service does not appear in the list of services in order to add this one to a new GPO.  There is no display name for this service, however CLI responds appropriately when you Net Stop NetBT or set to disable via  sc config netbt start= disabled

I would rather just choose the service and disable it using the settings listed for group policy without scripting it, however this would appear to be impossible because NetBT is not listed.  Go to any machine and try finding it.  Why isn't it there?  permissions?






The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol. DHCP allows for computers to be configured automatically to communicate with each other over an IP network without the need for manual setup by a network administrator. The implementation of DHCP relies on a DHCP server to hand out network configuration information to DHCP-capable clients that request an IP address (and other information required or useful in communicating with other devices on an IP network). In addition to an IP address, common configuration information served over DHCP includes a default gateway, subnet mask and DNS sever(s).