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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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Hi all,

I'm looking for a bit of help getting started with my HP 1820-24g switch .

my network plan :

sophos router eth1(lan and i configured the sophos router so : new interface eth4 ( mit VLAN ID :10 function.

i also sophos router configured dhcp scopes for to 200

so i connected sophos eth4 lan cable  -->switch port 1

so i have the native vlan 1, and  vlan 10(port 1-10 tagged) for lan  on the router.

my problem are:
1. if i change sophos interface(eth4)  Vlan funtion to only ethernet and i connect my laptop port 7 then get my laptop IP from sophos router dhcp server.

2.if i change sophos inteface (eth4) only Vlan fuction (vlan 10),then my laptop gets no ip from sophos dhcp server.

any idea and help?
Thank you
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i have a HP ProCurve 3400cl .I factory reseted ,but now i can reach switch any more . I thought it get automatically IP from my DHCP server. If i connect one of switch port my laptop,my laptop gets automatically IP from dhcp server, but i need to configure switch.
there is a serial port DB9 on the switch but unfortunatly i have no cable for it.

i looked arp and my dhcp server releases  but no clue of switch.

what can i do ?
Fresh install server 2008 r2, created password, set static ip to nic, {broadband router, lan dhcp diabled, firewall off, ip range set to 1 ip, nic ip settings ip, subnet mask, gateway (routers ip), dns set to dc ip - or left blank, IPV6 unchecked, computer name changed to : Server,  System restart, Updates set to auto download, remote desktop enabled (more secure), add roles checked active directory services, popup to install .net so ok then next does the role install, restart after then run dcpromo from start menu search, create forest name FQDN: JRSS.NET (no errors after checking) function level 2008 r2, database, logfile, SYSVOL all left at default, set restore admin password, nic dns 1 now set to so changed it to, dns opened and forwarders set to,,,, interface set to only listed ip, dhcp role installed, dns entered, clear that and enter then verify and all is fine, next, ipv4 list, next scope add, name home, def, home, start ip end ip, gateway (optional) (routers ip), next no WINS, disabled IPV6, restart and device ie router, dc. next i create a PROFILES partition with Users Folder created and shared with setting set as everyone with full access, share name \\SERVER\Users, next i create an OU: Home Users and Guest Users, in Users I Copy Administrator …
I had this question after viewing Cisco ASA 5505 and Microsoft DHCP superscope.

Hello everyone, i am new to this forum and i have a question similar to this one.

i have a Microsoft Sever 2008 R2 which is the DNS and DHCP . IP Scope is -
its sonnected to a switch and then to an ASA5505 that goes outside to the internet. its all working and fine. but then the users using WIFI and cable to connect and the IP range is all but used up so i want to extend. i created a supercope in microsoft sever 2008 r2 and its range is - also on the ASA i created an interface name inside1 and assinged it an ip of /24

how can i get this to work using the ASA?

Hi - i need help setting up a guest wireless network on a different subnet from the work wireless network.
We have 2 D Link AP's that have the ability to have up to 4 SSID's with different VLAN's, DHCP is coming off a Windows 2008 server and all are connected to a Netgear switch that has VLAN capability.
Please can someone help me with this setup - is it even possible to have a separate guest subnet with this setup?
The problem occurs when the computer is restarted or turned on, causing loss of IP. It is reviewed and there is an IP that starts with "169. ..." or that is duplicated.

This problem occurs with both static and dynamic IP addresses (dhcp).

It is solved by disabling and re-enabling the network or reconnecting the network cable.

The problem occurs in different computers, especially in win7.

The DHCP server is a Cisco 3650x

We await your help, thanks.
Hello everyone,
I just had and issue with a client where I ended up having to change the DHCP scope and network id.  I have changed the DVR to match the network and then after that it is now prompting me any anyone else to tries to log into it or make any changes with an admin username and password and I know I did not configure it to do that.  Also no one knows who this was purchased from which makes this even more challenging.  I have reached out to a camera company to see what could be done and then he recommended that I do a firmware upgrade to default factory reset it and the website he directed me to did not have any firmware for that device.  Does anyone know where I can either find  a firmware update or somehow default factory reset it.
I have 2 DC's running win 2008 32bit also Running DNS, DHCP with Domain Functional Level of Windows Server 2008.
I want to introduce a Windows Server 2012 as a DC and transfer the FSMO but I still want to keep running DNS and DHCP on th eolde 2008 32bit servers. ANY recommendation as of what steps should I take and should I also move DNS and DHCP to the new server?
Looking for a script that will go out and check if DNS is SET to DHCP. The script will run against all the computers in the network.  The output should only contain the name of Computers that are not using DHCP Option for DNS.

Thanks in advance
I'm helping a small school with limited resources set up some Cisco APs in their network. We want to keep the wireless devices outside of our internal network via a separate VLAN. I've had difficulty setting up this environment and could use some help.

Some older Cisco 720i APs A handful of old Cisco Catalyst 2960 Switches An APU2C4 appliance running pfSense acting as our Router/Firewall

What I tried:
I don't have much experience with the Cisco CLI, so I've been trying to set up as much as possible on the APs themselves via their web interface. APs have VLANs set up with an open SSID. I tried associating the ports these APs are connected to on the Catalyst 2960 switches with the VLAN we want to use. Also tried to use DHCP Relay (or "IP Helpers" in Cisco-speak) on the pfSense appliance and setup IP helpers on the APs, but I really have no idea what I'm doing at that point.

Any advice on how to actually get this done? Commands and step by step guidance would be greatly appreciated.
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The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

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We have observed that from time to time when a scope is disabled on server A, other scopes on server B are disabled. I guess because scopes go through a disable-enable operation, however some scopes are not reactivated.

How do we tackle this ? Any way to prevent this from happening ? Is it a known bug ? Is a hotfix available ? Anyone else has experienced this issue ?

Hey guys,
I am dealing with a client that has been down all yesterday as well as today with conflicting IP addresses.  I worked with Microsoft and they were able to find the mac address of another device that was giving out DHCP.  I have tried arp on various servers and could not find that mac even after pinging the broadcast address.  I have tried this command: show ip arp vlan (vlan number) | include (mac address) and all that it can really tell me is what the originating port is.  This lead me to two HP switches which also have the mac address but that list the trunk port as the originating source. I am getting absolutely no where with finding this.  Please help!!!!
I have Windows Server 2012 and I've been planing to install DHCP server in Windows since I have DNS and Domain in that server, but my networks utilizes switch's DHCP and I am wondering what is the best practices to manage DHCP is it to use core switch's DHCP or Windows Server DHCP?
Where i work has a large number of DHCP scopes. must be approx 40-50 its been left that way for a good few years apparently

I have just joined in past 6 months and just getting round to look at it now

Any DHCP scope clean up plans? Whats the worst thing that can happen if some are removed that have VLAN connections (one thing we're worried about) so i plan on taking an inventory first

I know i can use powershell to look for free addresses per scope can i use this to see addresses that are taken, then i could compare using HP IMC to see whats actually being used

Any ideas appreciated domain functionality is 2008
Does reconciling a DHCP Server has any impact on existing users and their leases?
Network LayoutHi,

 I have VMWare box that came with two NICs. I use one NIC for internal servers and workstations and they are on 192.168.1.x network.
 The 2nd NIC is directly connected to the back of ISP internet modem for the virtual machiens that need direct connection to the internet by getting public dynamic IP addresses from ISP DHCP server and it has been working fine.
 Recently these virtual machines (under "Public IP -vSwitch1") fails to receive public IP from ISP's DHCP server. If I assign a static public IP (we have a set of 5 public IPs given by ISP) to these VMs, they work fine. However if I configure TCP/IP properties in these VMs to receive IP dynamically, it receives 192.168.1.x number as if it is under vSwitch0.
 Today I spoke to tech support at ISP and they confirmed that they still give out dynamic IP addresses to any device attached to their internet modem as long as it is set to receive dynamic IP.
So far, I have restarted these VMs, switched NIC between vSwitch0 and vSwitch1 on VMs, shutdown & start, even created a new virtual machine and assigned NIC to vSwitch1/Public IP group, but to no avail.
I have not restarted VMWare box yet.

 Any suggestions?

I have a 3750G issuing DHCP to a bunch of voip phones and mostly seems to work.
I have option 66 configured
ip dhcp pool Phones
   option 66 ip

Open in new window

but when I look at the phones GUI I see this odd value
	DHCP Option Server Path	@(HH

Open in new window

I'm not even sure what question to ask other than is there a different way I'm supposed to set option 66?
i.ve scom 2016 and need to specify some service that i need to show using the visio to make dashboard. so if i need to check health of the DNS service in my 3 domains how can i do that and shall i choose. also if  i need to check the status of my DHCP subnets can i do that?
i'm using visio 2013 and the scom addin installed but it's for system centre 2012 does it make any effect?
also if i need to just click on the service from the visio should it gives me the status of this object only?
Hi Experts,

I am getting ready to demote a Domain Controller from our domain.
Yesterday I removed this server from the DNS listings of our DHCP clients.  The only DNS servers assigned were the 2 other DC that were previously there and working fine.

Once their leases were renewed and they received these settings, the internet was hit or miss.  Some sites didn't work at all while others took forever to load.  It was clear to me at the time that it was looking for the other DNS server but it was not listed in their DNS servers and even if something was referencing it, it was still available.

I ended up putting it back into the scope and all has returned to normal.  Here is my question:

Why did this happen?  Does DHCP still know of it's existence even though I removed it?
If and when I demote this domain controller, will this automatically remove it from DHCP or will/or should I do this step again after?

Thank you for your help

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We are expanding the internet access to the entire school body and we will need 800+ ip addresses to accommodate them all. the existing DHCP range is with a Mask of the default Gateway is at if i open the mask to it moves it to a class B network, so does that mean i have to change my existing ip address range from 192.168.x.x to a class B range? If i set the range from to using subnet mask of I will have to move the Default Gateway from to something outside the range. i tried to start the rang at to keep the DFGW at but i get an error saying the gateway is not on the correct subnet? Is there a better way to do this?

Thank you
I had this question after viewing UUID for OEM Bios no embedded Ethernet mac address , after vista II OS , is it protecting or abnormal ?.


This topic case can be closed as:

UUID is modifiable feature as many as no limited with motherboard changed .  Vista II DUID with IPv6 can not be changed followed rules of NIC and IANA.

Question recreated as:
Vista II DUID ahead of dhcpv6 valid from my ISP Apr. 2014 , broadcasting to the networks, taken away authentication  and rollback me as its client of "server" .  ISP prolonging for treating this since 2012 with dhcpv4 only to later it having had dhpv6 .  The Modem.ISP only can release an fe80:: layer IPv6 to the gateway and as dns.ipv6 by the ipcfg /all command reported.

Whose DHCPv6 broadcasting DUID embedded OEM motherboard.mac replaced off and lost ?
ipcfg modem dns
Gateway assigned fe80:: local layer IPv6 from the stranger upper device , unauthenticated "Server"  device / platform?
modem gateway IPv6 fe80::

Your writing  back are expected on  how to modify this and calculate the mass caused inside the complexity .  Let have a valid IPv6 directly from ISP.   ISP routering service not relied these years by 1996 , because the poor firewall and account Username duplicated in high/low case. While the local wireless …

We have two DC both are running 2008 R2

DC1 - All FSMO roles, AD integrated DNS (VM)

DC2 - DC, AD integrated DNS (VM)

SRV1 - DHCP windows 2003 (VM)

I want to add 2012 R2 (Physical) as DC and want to move DHCP to 2012 R2 server.

Need to migrate FRS to DFSR.

Show question is should I migrate FRS to DFSR first before adding another DC running 2012 R2 or after adding it?

or add 2012 R2 first then move DHCP to 2012 R2 and then migrate FRS to DFSR?

Instructions to migrate FRS from another SW topic https://blogs.technet.microsoft.com/filecab/2014/06/25/streamlined-migration-of-frs-to-dfsr-sysvol/

Can you also provide me working instructions on migrating DHCP from 2003 to 2012?
Also, I need to add processor on existing DC servers which are VM any issues doing that specially on DC? I have tested on another 2008 server and did not cause any issues?

Thank you
This morning when I got to work a couple of machines could not access the internet, including my own. The only common thing is that they have all got static IP addresses for RDC connections.

main subnet =>
DHCP scope => -

my static IP =>

On the PC's which have a static address if i change them to DHCP everything works. If they are static they are not able to access anything external. Internal Sites work fine. DNS lookups work fine for both internal and external sites.

I have tried getting a dhcp address on my PC, then setting the exact same IP address manually and see the same restrictive behaviour. Everything was fine yesterday evening when we left, nothing has been changed. i cant see any updates have occurred. i have checked router settings and rebooted several times. still no joy.

Any Help would be appreciated.



I'm planning to demote windows 2003 DC this weekend and after researching the process I believe following needs to be done and want to make sure my understanding is correct.
Current Environment:
DC2003 running Windows 2003 (AD, DNS, DHCP, File Server)
DC1 running Windows 2008
DC2 running Windows 2008

Ran DCDIAG report attached.
DC1 has all FSMO roles.
All three domain controllers are global catalog servers.
Domain Functional level: 2003 (screenshot attached)

Steps to demote:
Remove DC2003 as a global catalog server. (maybe reboot afterward)
Change DC2003 DNS to point to DC1.
Run DCPROMO and keep this as DC2003 as the member server.
After successful removal change domain functional level to 2008

Should this change affect DHCP? Can I move DHCP role at the later time?
Am I missing anything?

Can someone please review this and let me if steps are correct?

Thank you,
Does anyone know of a cheap and good program to use to monitor IP address on your Network?






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).