DHCP

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 taken over a network that someone else setup.  I have VMWare with 3 Windows 2008 servers running on one box.  My local network has IP addresses in the range of 10.0.0.1 through 10.0.0.254.  My domain controller is also my DHCP server.  For some reason the person who preceeded me assigned the following network addresses to the servers, 10.0.0.2, 10.0.0.3 and 10.0.0.7.  I can access the VMWare client through 10.0.0.7 or 10.0.0.8.  Would I cause any problem if I were to change the IP address for the server from 10.0.0.7 to 10.0.0.9?  I have had a couple times when I have had problems with the server and could not access the VMWare client through 10.0.0.7 so it would be more convenient if the server had a different address.
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hello,
i've actibe on win 2012 r2 (3 DCs) and installed dns on it, and dhcp on other win2008 r2 server when i run nslookup command to get the hostname of pc ip i got an error like that:
 primary name server = localhost
        responsible mail addr = nobody.invalid
        serial  = 1
        refresh = 600 (10 mins)
        retry   = 1200 (20 mins)
        expire  = 604800 (7 days)
        default TTL = 10800 (3 hours)
*** No internal type for both IPv4 and IPv6 Addresses (A+AAAA) records available

so what's the missing configuration that can fix it?
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I have a Shoretel MPLS network and a Windows data network. For the past year these networks have been physically separate and distinct but on the same racks. The problem is there is a large user community with many of them not technically savvy. Under each desk are live jacks for their workstations and their phones. Sometime over this past weekend a cross-connect occurred on the production floors of the building.

As a result, I have had twelve workstation that I know of dump static IP addresses and pull a DHCP lease instead (first oddity since none of them have power saving enabled on the NICs). I attempted to reset the winsock stack but no change in behavior. All workstations are protected with layered A/V and malware protection. Second problem is now the data network is offering phone network DHCP. Obviously someone has plugged in a rogue switch or messed with under desk cabling. It could be as easy as looping a connection between jacks.

All my workstations are identical build windows 7 Pro systems. All of these systems have been assigned static IP addresses, some for over a year. Why would a workstation that has worked perfectly on a static IP suddenly drop it and try for DHCP? And it's not just one or two - it every workstation I've been called about so the behavior is distributed.
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Hi,
So currently a site has no VLANs configured and is on 192.168.1.0/24 subnet. We are changing this so they have several subnets for servers, workstations, wifi, printers, so for instance 10.10.1.0/24, 10.10.2.0/24 etc etc.
Also moving the DHCP server 2003 R2 to a new server 2012 R2 server before upgrading to server 2016.

What is the best practice you would say at setting the new subnet up on the new DHCP server?
Do i just create a superscope with the different subnets and leave the old subnet off it completely? OR import the current DHCP config into the new server, then create a new scope with the new vlans, disable the old scope and test internet access?

Thanks
Craig
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We have two locations not connected.  I split two DHCP servers.  Shut down the DHCP server service on the 1st server.  Withing 5 minutes the 2nd server had address leases.   One server is 2008 R2 the other is 2012 R2

At the second location I did the exact same thing.  The 1st server has had DHCP Server turned off all night.  The 2nd server does not have any leases.   Both servers are 2008 R2.
I've logged on to a few of the computers that have the shutdown DHCP server as their server.  They show active leases that expire in a few days.

Why are the two locations not performing the same?
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I have a multi host cluster using a Distributed Switch on esx. I have 50 ports and 29 available. Currently there are at least 6 vm's running server 2012 with static LAN addresses and have WAN connectivity.  I just created 6 more vm's and assigned static addreses but cannot get WAN. I have verified subnet/gateway etc. I am able to ping the domain controllers and gateway when there is a static assignment. When set with a DHCP address, the servers have WAN. I have tried to remove the virtual NIC, reset tcp/ip stack. I cannot figure why i get no connection on a static address but do on DHCP. I have even tried to enter the DHCP settings manually, exactly the same. Any ideas?
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I'm testing our AD environment.  We have 3 DC's all are DNS servers.  2 of them are DHCP servers.  Both DHCP servers have all 3 DNS servers listed in the DNS server settings of the DHCP scope.  The server that I'm shutting down is listed first in the settings.

When I shut down one of the DNS/DHCP servers and then reboot a workstation, the workstation doesn't get a new logon server
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Hi,

I have two routers, one with a WIFi network that the children connect to via DHCP and another with one that the adults connect to, also via DHCP.

I want to be able to limit the bandwidth of each of the children's devices so that while I'm working, they don't suck the network dry. Asking them is out of the question so I need to do this automatically.

Their router, a Dreytek 2820 is set to:

IP: 192.168.19.100
DHCP Start: 192.168.19.126
Pool Count: 24
Gateway IP: 192.168.19.1

Our router: Dreytek 2860
IP: 192.168.19.1
DHCP Start: 192.168.19.101
Pool Count: 24
Gateway IP: 192.168.19.1

The trouble I'm having is that they are picking up an IP from our router .101 onwards rather than the router they are connecting to via WIFI which should be .126 onwards.

I had assumed that if they connected to the router, it would dish out the IP's.

I've tried Binding an IP to a MAC on ours which sometimes works but isn't 100% as they often revert back to the DHCP IP and therefore bypass the limits.

Where have I gone wrong on the set up here?

Thanks for your help.
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Just a question: if you dc promo a 2012 server r2 , would it hurt anything to just have the server sit for a week or two without installing any roles such as dns, gc,  or importing dhcp or any of the fsmo roles? Basically can i dcpromo the server and just let it sit? Will this cause any problems in the domain?
-i have read that dcpromo has been deprecated and now use powershell, but i just want to know can the server sit after it is made a domain controller?
-why you ask...i just want to know!
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Hi, we have 2 domains, domainA.local and domainB.local and are joined by sites and services, and each domain has two DCs (this is all just for information purposes)


The issue is, in domainB.local we have 2 DCs, both with DHCP roles installed, say we add a dhcp reservation or scope on the DHCP on one of the DCs, it isn't updated to the second DC; any ideas why? I am not sure if it is working on domainA but wanted to provide as much info as possible.
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I have updated a few of my computers on my network to Windows 10 and now some of them are unable to get an IP from our Windows Server DHCP servers. When the local lan (no computers are using wireless) is enabled, the device will get assigned a 169.254.X.X address. DHCP is working fine for Windows 7 machines. Any ideas what could be causing this or how to work around it?

Also, should note that if I set IP address manually it works fine. And the scope has plenty of free IP's to lease (about 37 used out of 100).

Thanks in advance.
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Hello,
Does anyone know how I can fix this issue with our Exchange 2007 on Win2003 server?  Beginning early this morning all connections from outside our LAN are lost or down on our Exch2007 Hub Transport server.  After checking all services it came down to restarting the DHCP client service and the Hub Transport server is back online.  It is very sporadic and I can't seem to find out how to fix this.

Outside email stops arriving and I'm unable to access the Exh2007 server via iPhone or OWA.

Thanks,
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Hi,

Recently had a perculiar issue with clients on one of our customers networks that stopped being able to lookup names on the internal network, losing network drives, gpo etc as a result.

DHCP is served by windows server 2008 DC with DNS service also hosted on this with the relevant pointers to this set up in DHCP.

We ended up having to statically set the DC name in the HOSTS file until I looked at this onsite this morning, I noticed a nslookup was resolving the router as the dns service instead of the DC. Powering off the router and running the same nslookup and it resolved to the DC. DNS and DHCP were both disabled on the router.

I made a change to the Interface in DNS as it was set to 'Listen On All IP addresses' I changed this to 'Listen on specific IP' which was the IP of the DC(Itself). Flushed the cache on the clients, restarted them they got the gpo, drive mappings, and I could resolve the server by name.

However, a nslookup still resulted in the router name rather than the DC name, despite obviously being able to resolve hosts on the network.

I then disabled ipv6 on one of the clients nics and hey presto a nslookup resolved to the IP of the DC, if I re-enable ipv6 on the nic it reverts back to resolving the router.

My thoughts are that the client isn't able to resolve the DC by ipv6 so it is reverting to the server for some reason, perhaps because of forwarders/root hints set up in DNS.

They are up and running again but I have noticed …
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We are replacing our DHCP server and have come across a problem I'd like expert advice on.
 - Our current DHCP servers (DC1,DC2) are providing leases without issue.
- We have configured new DHCP server (DC3, DC4)  to replace these servers.

After deactivating scopes on DC1/2 and activating on DC3/4 we are finding the following (after ipconfig /release & renew);
  • Clients on the same subnet as DC1/2 obtain leases as expected
  • Clients on a separate subnet/switch timeout when trying to contact a DHCP server, respond OK once DC1/2 scope is re-activated

I have checked a related switch and there is no ip-helper command configured. My question is - can anyone explain why this would work with DC1/2  and not DC3/4?

Thanks in advance
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We have a domain controller running Windows 2012 Server and it's also our DNS/DHCP server.  Non Windows devices acquire a DHCP lease, but fail to register in DNS.  Yesterday I added a non Windows device to the network, which immediately showed up in DHCP, but not in DNS.  This morning it finally did show up in DNS.  I added another device today and change the scavenge setting to 1 hour, but it still does not register with DNS.  I do have it checked to dynamically update DNS.

Maybe it tomorrow it will magically show up in DNS, but shouldn't it immediately be added to DNS when a DHCP lease is created?  How can I get this to happen without manually add it?
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All,

I have a project to use DHCP on Servers.  Has any one done this in their environment, any issues or risks?

Thanks!
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I migrated my DC from 2003 to 2012 R2 recently, and have been having a real bear of a time with workstation connectivity. 2003 had a clean demotion(so it seemed), I exported/imported DHCP, synced DNS, and seized FSMO properly. I have looked through ADSIEDIT to see if there were any stale records of the old DC. There seems to be something funky with DNS and/or DHCP, as I am receiving event ID's 5781 NETLOGON, and 4013 DNS-Server-service, 1054 Group-Policy, and 10020 DHCP-Server warnings/errors.
These events are occuring when reboots are not even happening. Just all day long.
On Event ID 10020 DHCP-Server warning, I do not have iipv6 enabled on my NIC. All other NIC's disabled. ipconfig /all shows no ipv6 IP address.
Workstations are consistently and intermittently loosing connection to internet with Event ID 1014. This does not occur at the same time for workstations.
What I have done so far...

I have disabled all Windows software firewalls.
My DC points to itself as the DNS server.
DCDIAG reports no errors. (also with /test:DNS)
Have disabled slow link detection on workstation GPO and DC GPO.
Disabled autotuning.
Disabled task offload on DC
Created a _msdcs zone in the root of Forward lookup zones.

This is a solo DC. Solo DNS (active-directory integrated)
Forwarders point to my ISP which is Google. (8.8.8.8, 8.8.4.4)
I have not tried disabling recursion, as I don't really see that as a troubleshooting resolution for this problem.

After migrating the …
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Hi,
We have:
SCCM 2012 R2
DP in remote office with PXE options enabled (VM within HyperV)
DHCP is on a Cisco switch
Option 66/67 set on the switch, option 66 ip [address] & option 67 ascii smsboot\x64\wdsnbp.com

When we try to do a PXE boot it displays the following error: PXE-E32: TFTP open timeout, see screenshot attached.

We use to have DHCP on the physical server at the remote office and that was also the DP and this worked fine. Since moving the DP to a VM and the DHCP to the Cisco switch it is no longer working.

Thanks
IMG_20170614_122728--003-.jpg
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I recently concluded a successful domain migration from windows Server 2008 to Windows Server 2012 R2 Essentials.  The new server is acting as a DC and is operating well.

However I have a problem Adding roles and Features.  I tried installing the DHCP Role on 2012 in order to migrate DHCP from 2008 but I keep receiving the following Message:

"The Request to add or remove features on the specified server failed.  The operation cannot be completed because the server that you specified requires a restart""

It does not appear to matter which role or feature is selected   The result is the same and numerous restarts have not resolved the problem,  

Has any one come across this problem before and resolved it?  Many thanks
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Server is domain controller in cloud, connected via VPN
Server is recently migrated - 2008 on premise to 2012 in cloud.

DHCP is running on local Cyberoam router
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Which VLAN   to enable ARP inspection

I would like to know which VLAN to enable ARP Inspection. Is it going to be on the same VLAN where the Trusted DHCP server resides on ?
Or on every VLAN in the network ?

Switch(config)#ip arp inspection vlan <VLAN Name>



I also wants to know about the DHCP Option 82 configuration.
Using IP helper-address <IP address> is enough or  we need to add:
ip dhcp relay information option

Thank you
0
Hi All,
I have a Cisco 2600 router with 2 Ethernet and 1 serial interface, I have the fa0/0 connected directly to my internet modem(Comcast) and have the interface setup as a dhcp client to the modem. I have the fa0/1 interface connected to another cisco switch.
The fa0/1 interface is assigned a 192.168.1.1/24 ip and its also acting as a dhcp server to the internal hosts..
The Comcast modem IP is 192.168.100.1 which I had to get from Comcast.
I also have an ip route 0.0.0.0 0.0.0.0 192.168.100.1
I don't have any NAT running, not sure if I really need it or not my internal LAN is working fine, I can ping the gtwy, the clients are getting ips from the dhcp server..

I'm having the hardest time connecting to the internet, not sure what I'm missing, mind you I'm very new to the world of cisco networking so just experimenting in a lab environment and help would be greatly appreciated.

thanks..
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Hello,

We are deploying windows 7 with MDT. Everything is going good. We are using USb to deploy.
But everytime machine restars, it throws error
"     A connection to the deployment share (\\servername\DeploymentShare$)
                     could not be made.
                     DHCP Lease was not obtained for any networking device! Possible
                     Cause: Check physical connection"
when we click retry it works.
IS there any solution for this?

Thanks
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I am running the initial configuration dialog on a Cisco 891 router.

I will be using GE 0/0 to connect to my ISP.  I want to do this through DHCP.

Enter interface name used to connect to the
management network from the above interface summary: GigabitEthernet0

Configuring interface GigabitEthernet0:
  Configure IP on this interface? [yes]:
    IP address for this interface: dhcp
% Bad Internet address.
% Enter an Internet address of the form 'X.X.X.X', where each
% letter corresponds to a decimal number between 0 and 255.

    IP address for this interface:

Open in new window

How do I specify DHCP for that interface?

Thanks!
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I have cisco 5508 lan controller and 2702i WAPs with static IP address. I want to remove static ip address and assign through cisco ios dhcp server. I'll do the following:

On cisco switch:
ip dhcp pool <pool name>
network <ip network> <netmask>
default-router <default-router IP address>
dns-server <dns server IP address>
option 43 hex <hexadecimal string>

Then go to WLC GUI and go to each AP and click "Clear all config"

On switch the ports are configured as:
switchport access vlan 111
switchport mode trunk
switchport trunk native vlan 111
switchport trunk allowed vlan 9-11, 111
spanning-tree portfast

All WAPs are in flexconnect mode.

Are these steps correct? If not, please list detailed steps. Thanks.
0

DHCP

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).