DHCP

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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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Hello, I have layed out the following tasks but would like to have your advice in it. Thanks for your help.
I heard that I cannot change IP address one the server is a domain controller ?

Is the following makes sense:

(Task 1) Create a new VM based on Template TEMPLATE-08R2      
(Task 2) Computer name as DC01      
(Task 3) Give a temporary IP address 192.168.1.5 and fully patch it.      
(Task 4) Promote DC01 into a Domain Controller      
(Task 5) Once confirmed replication to DC01, transfer FSMO roles from DC03 to DC01

Current Roles:
Schema master         DC03.domain.local
Domain naming master  DC02.domain.local
PDC                   DC03.domain.local
RID pool manager      DC03.domain.local
Infrastructure master DC02.domain.local

(Task 6) Backup DC03 DCHP Database      (Comments) http://technet.microsoft.com/en-us/library/dd759235.aspx
(Task 7) Backup Tacacs.net Configuration      (Comments) C:\ProgramData\TACACS.net\config
(Task 8) Disable DC03 DCHP Server
(Task 9) Restore DC03 DCHP Database into DC01 DHCP      (Comments) http://technet.microsoft.com/en-us/library/dd759235.aspx
(Task 10) Assign DC03 IP 192.168.1.3 to DC01      
(Task 11) Install Tacacs.net into UPIDC01      (Comments) Restore TACACS.net configuration
(Task 12) Assign DC01 IP 192.168.1.5 to DC03      
(Task 13) Test      
(Task 14) Once confirmed all is working dcpromo down DC03
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I want to create a DHCP scope for only a specific brand/type of device. They all have similar mac addresses. Can I create a scope that will only serve mac addresses matching for example  01:01:01:*  ?
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Hi there,
Running server 2008 ent R2 domain with 2 DC server 2008 and one  DC server 2012 ent datacenter all clients windows 8.1 x64.  On my physical site I was running 2 subnets 10.10.10.0/24 and 10.10.2.0/24.  Things were working fine. Till yesterday any computer attaining IP from subnet 10.10.2.0/24 is really really slow logging in, and the same computer would act accessing the network resources.  I also tried to rejoined to domain the computer which already had 10.10.2.0/24 IP, it says the domain does not exist.
Steps:
-I manually put the IP from subnet 10.10.10.0/24 and restarted the machine things were very well, no lagging while logging on, can access the network resources etc.
-I disabled the scope for 10.10.2.0/24 under superscope of DHCP server and re-added just to make sure the problem goes away, the problem persist while any computer gets the IP from this subnet.

I had no issues before.  This problem appeared recently.  Could it be the new DC server 2012 doing something odd?

Need help with this odd problem.
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Here is my setup:

Primary Subnet is 192.168.0.x
Secondary Subnet is 192.168.20.x
DHCP server is 192.168.0.13 and has multiple scopes including 0.0 and 20.0
Router has 192.168.0.16 and 192.168.20.1 (secondary) as its IP Addresses

So here is the question, currently the DHCP server offers leases to many different subnets but they are all vpn tunnels without issue. The 0.0 and the 20.0 subnets are both on the same physical network. I have a virtual computer assigned to 192.168.20.2. I have a wireless AP assigned to 192.168.20.3. I want to give the wireless users an address in the 20.0 network but have been unable to do so.

I have been working on this for a few days off and on now but have made no progress. I have tried to add helper addresses on the router to point back to the DHCP server but this works with or without this being configured.

What am I missing here? If a client is connecting to the AP on the 192.168.20.x network should the DHCP server not see this and assign it an address in the 20.x network?

Any advice would be greatly appreciated.

Thanks,
Ryan
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I am by no means an expert, but have basic knowledge of setting up a single IP adress range less than 250. Our company was taken over and merged with another. I need to create a new domain and i would like to deploy ipam. There are in excess of 350 users and devices. So here are my questions :

1. If i create 2 scopes on one dhcp server, what will determine who gets what IP ( the 2 ranges would be 180.10.100.xxx and 180.10.101.xxx with a subnet of 255.255.254.0.
2. Do i create a superscope by combining the 2 and then the same question remains. What will determine who gets what ip?
3. I am assuming that the 180.10.101.xxx will not be able to ping or see devices on the 180.10.100.xxx range.

I will be running 2 domain controllers for fail over with both running dhcp and DNS. I've hit a wall on this. Please help.
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I am small ISP and I have a working NPS Radius server who is controlling my DSL subscribers. Can I make the NPS server to relay ip addresses to my subscribers DSL modem ?
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I was getting complaints of duplicate A records for a while so starting digging in.  The DHCP audit log will show DNS Update Failed with a 9005 error.  I had previously cleaned up the structure by rebuilding the _MSDCS zone at the top level and confirming all the SRV records exist (supported by DNS Lint and DCdiag verbose DNS tests). Also set the zones to replicate across the forest and use secure updates and consolidated a bunch of reverse zones into a two-octet one (new one would be 99.172.in-addr.arpa as example). So reading up on it I decided to add all my DHCP servers into the DNSUpdateProxy Group, create an account to bind credentials on my DHCP servers (some happen to be DCs), set the DHCP scopes to "always dynamically update...", "Discard A and PTR records when lease deleted", and "Dynamically update DNS A and PTR for DHCP clients that do not request...". Scavenging is set to 7 days refresh/no-refresh on server and all zones.

The problem is really prevalent on our VPN scope- you know the deal folks are connecting and disconnecting all the time. We had the scope set to a 2 hour lease.  So yesterday I changed the lease to 25 hours, and set Scavenging to 1 day. Thought this would resolve it. But we are still getting duplicate A records some even with the same time stamp!  Happening in other scopes/networks as well that have longer leases.  I've noticed different security on records that were even time-stamped in the last day since the changes. Some have the client …
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I have migrated my DHCP instance to a new 2008 R2 DC from an old 2003 DC. All my scopes are in there and correct I have been able to authorize the instance but still can not get my PC to find it when I release and renew. I flush the DNS and stil no luck can someone help me with what I am missing?
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Hello,

When we access the DHCP console via RDC on our DHCP server, navigating through the tree is extremely slow.  I mean, you expand the domain to see the scopes and it takes forever.  Further expansion of scopes and such also takes forever.  Has anyone ever experienced this.  It was not this way at my last job.  We are a windows 08 AD environment.

Thanks
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I have an ipv6 network 2001:db8:85a3:: /80
I want to setup a DHCPv6 scope.

Starting range 2001:db8:85a3::2 /80 ending range 2001:db8:85a3::9999 /80
This scope above can basically give out 9998 ipv6 address.
Please confirm if  this is correct.

Also say I want to add 100 more ipv6 address to my above scope how will it look.
Starting range 2001:db8:85a3::2 /80  ending range please advice
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I need to use 192.168.1.x for an inside network but can't seem to change the default IP of the management interface from 192.168.1.0 to something like 192.168.8.0.

I have tried using the CLI and ASDM to change the management IP to 192.168.8.1. This works partially. I am able to access the ASA via the console cable and use CLI. But a PC/laptop connected to the management port no longer gets a DHCP address. I have tried using a static IP but then ASDM doesn't load on the 192.168.8.1 address.

I assume that the Cisco ASA 5512-x must have a default network setting and DHCP service configured but can't find this is documented any where. This should be the most simplest of things to do but I am not finding the answer. Any help would be greatly appreciated.
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We have a windows2008 server which host AD integrated DHCP and DNS. We do regular file and folder backup os so drive.
Is this backup enough to recover the dhcp and dans in case there is an issue with current server?

i have seen several postings which talk about netsh and DHCP backup and restore.
What is the difference between nets and DHCP backup ?
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When changing lease time in a dhcp server, does that affect current leases or just new leases? Is there any documentation on this?
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Hello,
    We have the following Situation:
VLAN 1 = DATA
VLAN 20 = PHONES
Windows Server 2012 - DC & DHCP - This is a VM
Cisco 3560 Switch

Basically, we need the port that the Server is plugged into to be able to process DHCP requests from both VLANS. Unfortunately, each port can only belong to one VLAN, and even if we set Voice-Vlan as 20 on the port, it does not hand out DHCP addresses. If we set it as a member of 20, we loose data connectivity. How do we go about doing this?
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OK So I currently have a network running windows server 2003 with the following network config

Class C network
IP Range: 192.168.18.1 - 192.168.18.254
Subnet: 255.255.255.0

We have about 5-10 IPs free. I need to add more IP's to the network but not sure about how to go about it..

I looked at supernetting but am not sure how to set this up..  Is it possible to just change the current network config?

Any suggestions would be very much appreciated..  

Thank you!
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I need help thinking through this issue.

I have an AD 2003 environment - yeah I know, maybe next year I'll get around to upgrading :)

I have a single DHCP server with a number of scopes, but for the sake of this discussion, I'll say I have two - one goes to my main LAN and one to a separate VLAN on our Juniper switch that hands out a /22 scope for our VDI desktops.

We are woking on a DR solution.  The end product will be a VMware View host sitting at a remote site, normally connected to our network. I am configuring the servers with static IPs on our main LAN. The issue comes with the VDI desktops.  What I have done so far is to create another DC in our domain that lives on that VMware host. It is configured like any other DC. I have also installed DNS on it as well as a second DHCP server. What I was planning on doing was to go to the original DHCP server and change the scope size to cover 172.25.28.x -30.x instead of 31.x like it is now, Then I want to create a scope on the second DHCP server that looks the same, except it starts at 31.1 and goes to 31.254.  I had also thought about creating the same scope on both systems, but creating an exclusion for the 31.x segment on the first one and an exclusion for 28.x-30.x on the second one.

So my first question is - do either of these work and which would be the best way?

Secondarily, no matter what I do, how can I limit the virtual desktops in the production environment to ONLY get IPs from the first DHCP server…
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Hello Experts,

I am looking to export all dhcp server scopes from multiple Windows 2003 dhcp servers onto a new DHCP Windows 2012 server. As far as I know, Powershell is not an option here, because the Windows 2003 OS limitation, so netsh command is my only option here.

However, I am little confused here, as per my knowledge I only have 2 options:

Option 1, export all dhcp scopes and their value onto a CSV using the command netsh dhcp server xxxxxxx scope 172.x.x.0 show optionvalue > c:\SVDS006.csv

Option 2. run the command below to export the dhcp database from windows 2003 server and the import onto a dhcp 2012 server

netsh dhcp server  \\Name or IP Address export c:\w2k3dhcpdb all

Which method is prefer and why?

Need to be able to export then import all DHCP scopes from all Windows 2003 dhcp servers onto a single DHCP 2012 server. All DHCP scopes and their value options [DNS/WINS/domain name,router, and so on] must be imported onto the new DHCP Windows 2012 server.

Can you please provide an example where you export 2 scopes, one from each Windows 2003 server and then import onto a new DHCP Windows 2012 server?

Please provide as much details as you can in all steps
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Hi Team,
We have a standard domain network running server 2012.

now the problem is as follows
Any internal client when they ping is supposed to
mail.abc.com.au resolves to 192.168.4.2

Now what happens sometimes is that every morning when someone turns their PC on they might get an issue where out of blue the DNS starts to resolve to the WAN IP of our network

If i flush the DNS the issue is resolved

Has any one faced a similar issue.

And the strange part of that it happens even to the machines that were left in the office overnight s well and not only to the ones that were out of the office.

All clients get IP from DHCP server 192.168.4.3
and gives out DNS' as 192.168.4.3 and 192.168.4.4

Any ideas?
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I was configuring an AP and trunked interface 46 instead of interface 45 on a cisco switch.

I received a call from the building across the street saying there network went down.
What happens if you trunk an access port?

Was changed to
interface FastEthernet0/46
 description ap-lobby
 switchport access vlan 999
 switchport trunk encapsulation dot1q - ******Command I added on accident ****
 switchport mode trunk - **** Command I added on accident ****
 speed 100
 duplex full

When I removed the two commands above their IP Phone and Desktops seem to be back online but for some reason two users are still not getting a DHCP address and nervous I screwed something up badly. VLAN 999 I believe connection between several buildings in the city , a Metro Ethernet connection I think.  New to company so learning the topology of our network.
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We currently use a in house application to manage our IP space, reservations, and DNS zone entries.  I was wondering if someone could suggest any enterprise level solution to handle this as?

The software must be able to handle multiple subnets/vlans and be able to reserve an IP address for each subnet (maybe with a drop down?).  

We would also like it to run on it's own system and interface with Linux DHCP and Master DNS server.
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DHCP leases FIlled with BAD ADDRESS Entries
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Hello Everyone,

I am in the process of pushing new AV client to all clients from new ePO server in Toronto , and I am struggling with some DNS/network issues.

When a user located in Miami works from home it should get an IP address from the RAS VPN range in London or another VPN connection. Once the user is back to office, the computer picks up another IP address from internal network, however the DNS record is not been updated properly, therefore the only workaround, is  to manually delete the DNS record with the old IP address[IP obtained from VPN], wait for DNS replication and push the client again.

All users are either located in Miami or London, We have multiple servers across all regions, and the main AV server in located in Washington

For example

User A laptop setting:

Name: xxxxxxxxxx

Current DNS IP address record: 172.20.x.x

Current IP address assigned to laptop: 172.26.x.x

User B laptop setting:

Name:  yyyyyyyy

Current DNS IP address record: 1.0.x.x

Current IP address assigned to laptop: 172.26.x.x

The only difference I've noticed on the DHCP scope in Servers in London and Miami, is the DNS dynamic updates settings in the DHCP scope. Please see attached files

Can anyone point me on the right direction?
serverLondon.jpg
serverMiami.jpg
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Hello,

I would like to know your considerations or guidelines to upgrade my existing DHCP Server.

Right know there is an old physical machine with Server 2008 R2 Standard with Active Directory Services, DHCP and DNS Server roles.

We are getting a new hardware and we will install 2008 R2 standard as well.

The DHCP Server serves all desktops and laptops.

Thanks for your help,
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I have a network 192.168.111.0 /24 and I am running out of Dhcp addresses.  I do not want to add another Vlan even though I know that is an option.   I want to change the mask to /22 255.255.252.0 to gain the addresses that way.  My plan is to change the mask on the firewall LAN interface.  Create a new Dhcp scope on the firewall using the new range.  Dhcp devices will need to renew to get a new address.  For the static devices I need to change their mask manually.  My question is will I be able to connect to the static devices remotely when they have the old mask if I've made the change on the firewall already?  I am trying to do this without going to the site and want to verify it will work.  

Old range is 192.168.111.0 - 255

New range 192.168.108.0 - 192.168.111.255
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I have an existing network which i have configured it as below.

Servers/AP/Printers/etc
Static IP: 10.10.10.1 - 10.10.10.80
Subnet Mask: 255.255.255.0

Workstations
DHCP IP range: 10.10.10.81 - 10.10.10.253
Subnet Mask: 255.255.255.0

Now, as the company expands, I am running out of IP addresses for new workstations. How do I expand the address range/subnet? I have never faced this kind of environment before.

Thanks.
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DHCP

10K

Solutions

15K

Contributors

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).