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).

Share tech news, updates, or what's on your mind.

Sign up to Post

We have a printer issue that is having an issue connecting to a network via wifi. We have DHCP setup on our Sonicwall firewall, but we are not using this for the printers, we have setup a range of IPs outside of the DHCP scope, to be used specifically for these printers. One of the printers ( they are not able to print to, nor is it pingable. If we change it to DHCP and it gets another IP, we can print and all is fine. If we assign it another static IP from the range I mentioned above ( it prints fine as well. There JUST seems to be an issue with this one IP ( - Like I mentioned, no one else would be getting this IP because it is outside of the DHCP scope, and there is no other device in the building that is statically assigned this IP. Has anyone seen this type of issue? Any suggestions?
Hi Experts,

We are planning to demote a server running Windows Server 2012 R2 which is also a Domain controller. (i.e removing AD domain services etc and shutting down the server).
This server is also a DHCP server and was wondering if it’s possible to replicate the DHCP scopes configuration and DHCP scope options configuration onto another server? (ie. So that this service is setup on an alternative server so that the DHCP service is not disrupted)

In Windows 2012 R2 DHCP Scope policies, what is the difference between Vendor Class and Client Identifier? I have some devices that I need to setup a separate policy for and got the vendor id  from the vendor yet when I select vendor class, it has a drop down with only Microsoft options. Client Identifier does let me type information in though.

We have two DHCP servers, the OLD server and the NEW server.  We'd like to migrate to the NEW server, but we cannot get it consistently deliver IP addresses to our various subnets.

We have all of the appropriate IP-Helpers in our switches.  The behavior is as follows:

We are using Microsoft Server 2016 with Microsoft DHCP Server.  The server sits on ESXi host.  (different host)

1.  We turn off the OLD DHCP server and turn on the NEW DHCP server.  Scopes are enabled.
2.  In some cases, users will get new IPs right away.\
3.  In some cases, users never get an IP, they get a 169.254.x.x address.
4.  In all cases, if we switch NICs on the user's computer, they will get an IP.  For example switching from the docking station NIC to the laptop NIC will always give an IP from the NEW server.
5.  We can usually find the following message in the logs: "Your computer was not assigned an address from the network (by the DHCP Server) for the Network Card with network address 0xF4D108E45BA6.  The following error occurred: 0x79. Your computer will continue to try and obtain an address on its own from the network address (DHCP) server."

Any suggestions?
having recently had problems on our windows 2012 r2 dc, we carried out quite a lot of troubleshooting and resetting if things. one of them was to remove the virtual nic and add it back in again.

since then, when we reboot a client it cannot pull through ip addresses using dhcp. if i configure the ip manually, it works fine.

can anyone advise whether replacing the vm nic should affect dhcp, and if so how can i resolve this?

any suggestions much appreciated.
What is a better design regarding a company wireless network?

At my work we have 2 Guest Wireless Networks.  

1.  Guest Wireless (SSID) (
2.  BYOD Wireless (SSID) (

These 2 SSIDs are not routed to our company network in any way.  We have 2 wireless routers/controllers for high availability, our corporate network SSIDs provide DHCP from our internal DHCP server; but, both guest wireless SSIDs use the controllers for the DHCP server.  The only problem is that

Controller 1 has 1/2 of each individual DHCP scope and it has the default gateway of 102.1 and 103.1

Controller 2 has the other 1/2 of each individual scope and it has the default gateway of 102.127 and 103.127.

The Wireless Guest Lans work great and they have no connection to the corporate network; but, I noticed that if either controller is off-line the guest users must do an ipconfig /release to clear out the IP settings (default gateway for that SSSID in order to receive the correct IP settings from the other controller (Controller 2).  Hence the guest access is not a seamless fail-over process.  If you are connected to a controller 2 ( a unique gateway IP address) and already have controller 1's Default gateway ip address cacahed in memory … you will not be able to connect to the internet from controller 2 until you perform an ipconfig /release.  

Is there a better way to design the Guest Wifi Access for these 2 x GUest SSID's?  Currenlty we have 1 older WiFi …
Good Evening All,

This is my first post to Exchange Experts. I always tried to find my way by trying different solutions to the issues I had however I ma now facing DHCP issue on our new site with sonicwall product I have never used. Never used sonicwalls at all.

So I have below interfaces set:
Sonicwall Interfaces Config
At this site corporate WLAN on X2:V20 is our corporate WIFI with DHCP served from SonicWall with range 10.0.3.xxx to
X0 with subnet is a Corporate LAN with DHCP served from Widnows Server 2016 deployed by me with subnet range 10.0.0.xxx to

Now I have to merge those so the WLAN network take DHCP from the Windows server instead of sonicwall.
Sonicwall Model: NSA 2600

Any suggestions please?
Dear Experts,

I have a question regarding to the Window 2012 R2 server DNS, AD, and DHCP setup. Say I have a server setup with the these services DNS, AD, and DCHP. If I wish to configure a failover or a copy of this server, what will be a good way to setup? If I do need to setup another server will I need to keep it up all the time so in case the main server fails the backup can take over? How will I know if the user are on the main or the backup? Will the backup server cause conflict with the main server? Thanks. (sorry that I have so many question in one)
I have setup a failover DHCP server configuration in Hot standby mode between two Windows 2012 R2 servers in the same subnet. The Max Client Lead Time is 5 minutes and the State Switchover Interval is 15 minutes. The addresses reserved for standby is 0% because we don't have enough addresses.

When I stop de DHCP server on the primary server after 15 minutes the hot standby server switches the scope over to partner down and 5 minutes later it's serving out IP-addresses. Only now comes the problem / fun part. The stand-by server is leasing out correct ip-addresses from the scope, but it does it with the 5 minutes lease time as configured in the MCLT. He does this for the entire time the Primary server is down. So every 5 minutes it leases the same ip-adres to the client for an other 5 minutes. over and over again.

Is this normal behavior? I thought that after 15 minutes of switchover interval plus the 5 minutes of MCLT it takes over the complete scope and acts like it's the primary server.
Ive a new netgear jgs524PE switch and a netgear orbi rbk50 I would like help to setup correctly.

Currently the isp router is giving a gateway on one port of that runs to the Netgear orbi, The orbi in turn has created its own network on, my switch is connected to the orbi with an ip

I have nas connected to the switch, previously it was on but I guess that now needs to be changed?

What is the best way to set up here? The Orbi provides netgear circle which allows me to control the kids devices with devices on the orbi network. So I think the switch has to stay as currently connected.

I am not sure if I should have the Router providing dhcp.

Your advice would be welcome.

This is a home setup but I do require 1gb cable speeds as I zoom a lot. The  synology nas server needs to be accessible from outside.

My company currently it's moving to a new phone system and we are stock. our DHCP it's set to IP Scope 192.168.16.xx and I created a second Scope 10.11.0.xx so it can connect via VPN tunnel with the VoIP system of our another office (we are in So. Cal and the other office in Florida) now, To my knowledge I need to create the scopes and the services on DHCP so I can setup the relay to ensure that traffic can go from the 10.11 network using the 192.168 network as gateway and at some point  create a VLAN in my switches to route.

I did all the first part until before the VLAN part, I have some problems.

1-Computers on my Scope 192.168.16.xx are registering on the 10.11.0.xx I need to know how to stop them from doing that, I need to keep them alive but without merging

2-Do I need to create a vlan to route all my VoIP traffic ? we have layer 2 switches and the router it's managed by our ISP or Do I need to setup a a new port in my firewall with that subnet routing all traffic from 10.11 to the public IP

I have a VM running server 2008 R2 as my DHCP I have 2 virtual NICS installed one running on 192.168.16.xx and the other on 10.11.0.xx
I have RRA installed with IGMP installed, and my gut tells me that I did something wrong

I have not done something like this in years so if there is anyone that can give me some guiadence I will really appreciate it.
I have a server that has an IP address that was static but somehow changed after reboot was done on it.  The address was reserved on another DHCP server to prevent it from being used.  I am finding when I change the IP back to the static address it had, I get an IP conflict error showing up. I pinged the IP address on the LAN and I confirmed it is not being used by another device.  I was thinking DHCP is probably preventing me from using that address at this point so I tried disabling DHCP temporarily so I could then change that server IP back to it's static but I am still getting the conflict error.  

Any ideas what is causing this?
Spanning tree and working production environment.

Greetings, my work place has spanning tree and I have limited experience with Spanning tree.  I was charged with setting up new Wireless controllers and to route internet only traffic through a specific "Internet Only" VLan.  I have setup the configuration how the vendor suggested.  Basically:

- Create DHCP scope and assign the DHCP Gateway to a VLAN on the controller (created for the Guest VLan).  
- Then create a Vlan for Internet Only and assign an IP address to that VLAN(From the DHCP Scope).  
- Then assign that Internet Only VLAN to an available untagged port on the Wireless Controller.
- The assign an available IP address from the Internet only VLAN on teh wireless controller.
- Then connect that port (0/0/3) to the Internet Only VLAN with its own separate connection.

The problem, is that the Wireless controller is showing that port 0/0/3 is blocking.  Port 0/0/3 is the port connected to the Internet Only VLan.

Port Status
Slot-Port  PortType  AdminState  OperState  PoE  Trusted  SpanningTree  PortMode  Speed   Duplex  PortError
---------  --------  ----------  ---------  ---  -------  ------------  --------  -----   ------  ---------
0/0/0      GE        Enabled     Down       N/A  Yes      Disabled      Trunk     Auto    Auto    -
0/0/1      GE        Enabled     Up         N/A  Yes      Forwarding    Trunk     1 Gbps  Full    -
0/0/3      GE        Enabled     Up         N/A  Yes  …
I have two 3750 switches that are connected and working but here is my only issues. By the way I am very new to networking so please excuse me being naïve .

My issue is when I have a machine on a different subnet other than the main one 10.46.72.x DNS does not resolve even though I manually add and with a DHCP scope that I removed will not work. Can someone please tell me what  am doing wrong. Here is a copy of the config


User Access Verification

Base-sw1>show running
Base-sw1#sh ru
Base-sw1#sh running-config
Building configuration...

Current configuration : 3753 bytes
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
hostname Base-sw1
enable secret 5 $1$lwLf$CJoNDGBl4Ck6AAm/woBVM0
enable password secret cisco
no aaa new-model
switch 6 provision ws-c3750g-24ts
system mtu routing 1500
ip subnet-zero
ip routing
no file verify auto
spanning-tree mode pvst
spanning-tree extend system-id
vlan internal allocation policy ascending
interface GigabitEthernet6/0/1
 switchport trunk encapsulation dot1q
 switchport mode trunk
interface GigabitEthernet6/0/2
 switchport trunk encapsulation dot1q
 switchport mode trunk
interface GigabitEthernet6/0/3
 switchport trunk encapsulation dot1q
 switchport mode trunk
interface GigabitEthernet6/0/4
 switchport trunk encapsulation dot1q…
We are running 2 DCs which are 2008 R2. I know we will be replacing them in the next month or so.. lol
But for now we are seeing an issue with DHCP in that there are different computers that are getting the same IP address handed to them for some reason. Nothing has really changed in the DHCP setup that has been in place for sometime now.
We are seeing this more and more frequent for some reason.
Is there something that I need to check with dhcp to stop this from occurring?
We have a user that works at two locations. He is running Windows 10.
At location 1 he has DHCP with the DNS IP addresses he needs.
At location 2 we need to manually set static DNS for him to access some crucial applications.
We don't just leave the static DNS IPs on because this affects his normal internet access when at home or elsewhere.

I would would like to setup two command files (.CMD) that will change the DNS settings for his NIC per location.
 - Command file 1 - DHCP DNS
 - Command file 2 - Static DNS

What command line can I use to do this?

EDUCATIONAL QUESTION: I need to gain some knowledge our of necessity. Here is the situation. I do NOT know my way around things such as: 1. What the function of DHCP is; 2. Why port forwarding is necessary in some instances; 3. How to configure the ip addresses of my surveillance cameras; 4. How to start anew with my NVR and surveillance system.

I did not want to take the time to educate myself on these items since I would seldom have need for this knowledge. However, since I just got a new fiber isp and virtually nothing operates properly on the surveillance system I think that I must gain the knowledge necessary to do this myself. The company I purchased 70% of the system from will assist me somewhat but refuses to assist in any way at all for the cameras that I did not purchase from them. There are many free utility programs available that I have  installed, however I need the knowledge to determine what to do with them. I think you get the picture. What my question is: Can any Expert advise me of an online course that will teach me what I need to know to understand this area of technology that will not take me overboard? I will not be doing this for a living. I just need to know what is needed to enable me to restore my system to default and start anew and KNOW what I am doing. I wish I didn't have to take the time needed to learn this, but I cannot locate a person that can guide me through all that is necessary to get things up and operating again. I would feel …
In networking how does a computer get an IP address from a Windows DHCP server?  
Do you have to configure the main firewall/router to point clients to the Windows DHCP server usually?
I am having an issue where computers at my DR site are getting DHCP leases from a subnet on a separate VLAN (Though sometimes they pull the correct address). The server the computer shows the lease coming from is a server at my HQ and of course when the client gets the address it is isolated on the network and cannot access anything.

In my environment I have 2 domain controllers configured to handle DHCP. One server is at my primary site and handles DHCP for multiple VLANs at that location. The second server is setup at my DR site and handles only the DHCP leases for the DR site VLAN. I use Juniper switches and have setup the “IP Helper” address for the DR site VLAN to the address for the DR site domain controller.

I have the VLAN for my servers spanning across the 2 sites, so that when we have a failover situation I only need to change the gateways on my servers. So both the domain controllers that handle DHCP are in the same VLAN/Subnet.

All that being said, my phones at the site (which are on the same vlan as the PC’s) do not seem to exhibit the same behavior. They seem to consistently get the correct DHCP server and subnet lease.

To make things worse, I have had 3-4 instances where a machine at my HQ has randomly grabbed a DHCP lease from the DR site server. When I released and renewed the IP on the machines at HQ it quickly grabbed the correct address. However with the machines at the DR site the release/renew typically does no good.
We are upgrading our SBS 2011 to Server 2016, we are migrating both domain and exchange server. After going through some articles on web we have planned to do migration to 2 servers one for domain and dhcp and second for MS Exchange 2016. Our questions are

1. which server should we migrate over first.
2. when we migrate exchange do we require to do reconnections on the all desktops or the outlook would pick it up itself, we have outlook 2010 - 16
It is a Server 2019 Standard install. Two Questions:

1) Which server should be the DHCP server? The VMHost or the DC?
2) I thought best practices said you should not have two partitions ( a C and a D) on one virtual disk. So I created this VM with one fixed 250GB VD. Now I want to add a D: drive using a seperate VD. Can't find out how to do it.
Hello experts,

I am at a site and they use cisco WLC 5500 wireless controller and they have defined all the SSIDs , one of the SSID is the guest and I am checking the interface defined and it is clearly showing that it is on VLAN 50 the IP of the interface is given, plus the gateway which is same as the primary DHCP

I checked the core switch and there is VLAN 50 but just the vlan is defined but there is no SVI for vlan 50 and there are no DHCP services on the core, I checked the Microsoft servers and I do not see the scope for vlan 50. I am wondering how the clients are getting a dhcp IP when they access the guest SSID. I can not find this gateway or primary DHCP

This client also uses cisco ISE, I have access to the cisco ISE but it uses different IP and I do have access to it but I am not getting clarity on this network, Any suggestions on how to find this dhcp server or service will be great help.
We have a windows server 2008 with DHCP enabled. The scope properties display [] with start IP, end IP, subnet We want to know the easiest way to increase the number of IP addresses (example 1000 max) that can be given out by the DHCP server and make sure that everything is still routeable. For example, if one of the new IP addresses let's say is 172.22.2.x will that device be able to see the server at and access the gateway at We want to know how to do this and set it up properly.
Routing problem.... I do not think so.  What do you think?

I am trying to setup a new Wireless setup.  We are currently using HP MSM760; but, it is E.O.L. and we purchased an Aruba Wireless system to replace it.  I have never worked with either Wireless Systems and I am charged with:

1.  Learning how the HP System currently works.

2.  Duplicating the setup in the Aruba system.

I have been reading Aruba user guides  and setup you tube videos and I have everything connected and I have begun testing the SSID's.  The problem is that when I get any laptops or wireless devices connected they get authenticated and the device receives and IP address from the correct VLAN.  The Device shows up in the DHCP server and the IP address is associated with the Computer name; but, those wireless devices cannot ping anything on the network nor can anything on the network ping them.

I think that there must be a configuration setting that needs to be enabled.  Something that is unique to Aruba and outside the instructions I was given.  Aruba Support is stating that this is a network routing issue and they cannot help unless the main router can communicate with the wireless device.  I personally think that the reason there is a routing issue is because the Wireless Client is getting Authenticated into the Aruba system and a configuration setting is required to allow routing.

The thing is that the Aruba controllers can ping  devices that are on all of the required VLans.  The…
I want to detect non-domain computers in my network. Found scripts for this purposes. Which one - detects online workstations via Ip range and next one detects are they joined to domain or not. But i cant join them for properly working ) can anyone help?
$firstThree = "10.20.51"

1..254 | ForEach-Object {

    $address = "$($firstThree).$_"

    If (Test-Connection -ComputerName $address -Count 1 -Quiet) {

        Write-Host "$address is up" -ForegroundColor Green

    } Else {

        Write-Host "$address is down" -ForegroundColor Red



Open in new window

if (Test-Connection -ComputerName $computer -Count 1 -Quiet)
  if ((gwmi win32_computersystem).partofdomain)
    write-host -fore green "I am domain joined!"
    write-host -fore red "Ooops, workgroup!"

Open in new window







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).