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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Hey! I have a router problem. On last saturday, i got the new 1000mbit/s internet in my house. My ISP(called Digi, in Hungary .) Gave me a Huawei(Huawei EchoLife HG8242-B,) modem/router(?). I bought on monday a new TP link AC1200. BUt i was experiencing internet drop issues. (it lost connection after 30mins, and keeps doing that in that interval.) So I called my ISP, they came to my house on wednesday, and told that, the problem is in my router. So i took it back to the shop, and bought a new TP link AC1750 V4.0 on Thursday. But the problem still appear, and I've tried everything. Dhcp change, MTU size change, frimware upgrade/downgrade, DNS change but it still drops the connection on WIRED. The problem appears on every WIRED computer, at the same time. Before first my ISP came to my house, the Huawei was in Dinamic IP mode, but my ISP changed that to bridge mode, so now the connection is now, a PPOPE one. Problem still appears, every time, and ISP keep saying, there is no fault at their end. But it'S possible to get 2 wrong router? My ISP will come today too.  SO what should i change  to finally forget this problem?
The strange  thing is , from an old TP link 941N router, everything works fine.
Now, what could be the issue?
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Hello :-)
I am configuring dns scavenging in my dns / dhcp. currently the dhcp lease is 6 days, so according to the question https://www.experts-exchange.com/questions/29093013/DNS-Scavenging-Best-Practice.html I've defined the no-refresh and refresh values for 3 days each (50% dhcp lease). So the DNS option "allow automatic deletion of obsolete records" should be set to same dhcp lease (6 days)?

dns.JPG
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DNS scavenge with multiple DHCP lease times

We have the following configuration. Also attached is our DHCP configuration @ the top level. We have the default Server 2012 R2 options, "Dynamically update DNS records only if requested by the DHCP clients" with " discard A and PTR records when lease is deleted" ticked. We have credentials set for DNS dynamic update & our DHCP servers are added into the DNSUpdateProxy group. Scopes & counts as follows:

9 DHCP scopes with 1 day lease
12 DHCP scopes with 2 day lease
11 DHCP scopes with 8 hour lease
105 DHCP scopes with 8 day lease

Have done a lot of reading about the refresh + no refresh ideally being the same as the DHCP lease time, but assumption being DHCP lease times are same for all scopes. Our scenario is they are not, & so not really sure on the impact of different scavenging options

Majority are 8 day lease, so reading many blogs it mentions this should ideally match the total refresh. So values of 4 & 4 for no refresh & refresh, but then what is the impact of this on our scopes with 1day, 2day & 8 hour leases? Suppose the risk is they end up with duplicates until the zone is scavenged?

This is where I am thinking we should maybe configure DHCP to "always dynamically update DNS records" but they don't know if this actually required. My thinking is that if address is assigned to another computer DHCP can update DNS & we shouldnt have duplicates, then configure 4 + 4 days for scavenging. Or is this not …
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Hello Everyone !

I want to bind mac addresses with IP Address for all users in my network using different Vlans and for this I need a batch file which display IP addresses, mac address and computer name of all the users. please Help.
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I have devices that pull their IP addresses from DHCP which are not on the domain. I however need the devices to provide he DHCP server with a hostname -- make a DNS entries and update it when the IP changes.

Is this possible to do when the infrastructure is as the following:

ISC DHCP ( dhcpd )
Microsoft DNS ( AD DNS )

Thanks!
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Hi Experts,

what it the best way to build a test domain that is separate from out domain.

Is there a free cloud solution where i can just use for testing?
Essentially I just want to set up a domain, Domain controllers, DNS, DHCP from scratch and test putting the whole thing together for learning

Thank
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I have a client with a server 2016 domain looking after 15 machines and 2 hyper v machines all running Win 10.  The server is mainly acting as a file/printer share and one 3rd Party program running SQL. Emails are on Exchange Online.

The problem I am having is every day the client PC's loose connection to the server, cannot browse the internet and outlook cannot connect to Microsoft Exchange.  I can still connect to all the machines remotely via RDP, ISLOnline or Teamviewer etc, but internet browsing or connection to the server/exchange is not possible.

I suspect it is some sort of DNS/DHCP error.
I have tried restarting DHCP and DNS services to no avail.  The only thing that corrects this problem is a server restart.  Restarting the server will get the machines going for approx a day or a bit longer.  I have check all event logs on the server and the only Errors that are being generated are at the time I am restarting the server.

Each client machine has a static IP address and DNS settings set as Server and Google dns for backup
I have attached screen shot of Server IP settings and DNS setup, along with IPCONFIG of one of the client machines.
I am having to restart the server every morning before staff arrive to ensure there are no problems that day, but I need a more permenant solutioon.  Any advice would be greatly appreciated.



I now restart the server every morning to ensure smooth operation that day but I need to find a permenant solution.
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SBS 2008 server is having trouble starting DHCP, DNS services.
The power went out for longer than battery life, and the server shutdown properly.

When I try to manually start DHCP or DNS services, I get 'The service could not start due to timeout' error.

  • No MS updates since Jan 2018
  • Latest HP ML350 BIOS and ILO firmware updates are complete
  • Rebooted many times
  • BMR restored from May 2018
  • DHCP Client, TCPIP NET BIOS and Windows Event Log services are stuck on 'starting'
  • I can't get any errors from Event Log, because Event Log service won't start.

Can someone please help? I need to get this running ASAP.
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Hello everyone,
Setup: FOG 1.5.4  https://fogproject.org/
CentOS 7
Clonezilla Live: 20180329-artful
I want to make it easier to image PC’s. Right now I have to go into every machine to turn off “Safe Boot” and then using the servers IP address and “ipxe.efi” via option 66 and 67 on our DHCP server I can get an associated host to image from FOG.
If a host is not pre-associated with FOG we can still get to the FOG menu.

 

I would like to not have to turn off secure boot every time.
So far the only working solution which allows booting with all security turned on is Clonezilla.
Here’s where things seem to get tricky for me. I know FOG doesn’t natively support UEFI and Safe Boot but there is a Clonezilla PXE Boot option I want to try.
Website: https://clonezilla.org/livepxe.php
I’ve followed the steps listed here and in another site:
https://community.spiceworks.com/topic/352773-fog-and-uefi
They say to copy the necessary files (initrd.img, filesystem.squashfs, vmlinuz) from the “Live” folder from the Clonezilla Live image. For ease I put them in the tftp root.
tftp folder

 

Both mention configuring the pxelinux.cfg menu “default” which I’ve done using http and tftp destinations



They say to reboot and watch the clients go but it never happens. They mention the ability to select Clonezilla from a menu but I have no idea what menu. The only menu I’ve ever seen is the one shown above …
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Do we have any VBscript to take backup from DHCP database without using netsh commands in 2003 , 2008 servers
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DHCP server has stopped giving out IP addresses

Server: Microsoft Server 2008 R2

Issue: The DHCP server has been working up until Friday June 29th. Then it just has stopped handing out IP addresses to our desktops. I'm not sure what has caused this. I have shutdown the server and restarted it but that didn't resolve the issue.

I have tried downloading the Microsoft Rogue DHCP detection tool but when I launch the program it just immediately closes and doesn't do anything. Even if I right click on it and run it as admin.
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We have a child company that has the need to separate its IT infrastructure. The child company is still on the same campus, but in 2 different buildings. Would it be feasible to use a separate Vlan and create a separate domain with its own domain controllers, dhcp server, etc.? Would you do it this way or separate the other buildings completely with their own entire infrastructure (obviously way more expensive). Thanks for your input in advance.
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I have been tasked with assisting a friend setup a new server in his office. Ultimately we will have a domain environment with a Domain Controller, DNS, DHCP server. This is for a dental office so aside from that he will be running some dental software called Paterson Eaglesoft. I'm looking for the most cost effective way to setup redundacy, so in the event of hardware failure we could quickly (couple hours) get all everything migrated to another server host.
I am familair with VMware and HA, which would be wonderful in this case, but due to the cost of the SAN etc. this really isn't an option for him.
I'm considering purchasing a couple refurbished servers, stacking the local storage so that we have at least 2TB of storage and using using virtual servers (at least 2 VM's, 1 for the DC, DNS and DHCP and another for file and print services with the Eaglesoft SQL database installed).
It looks like Hyper-V might be the way to go here. I would install the VM's on one of the servers. What is the best way to "replicate" (in real time, as much as possible) the virtual machines from one host to the other? Again the idea is that if Host 1 crashes I could easily fire up the other server (host 2?) and get things back online as quickly as possible.
I don't have a lot of experience with Hyper-V. Is it safe to assume that I could enable something like this.
Hope this makes sense. Thank you very much!
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Hi Experts.
I'm trying to write a PowerShell script that would tell me if all the physical Wired interfaces (ignoring virtual interfaces generated by VPNs and Physical Wireless Interfaces) are set to DHCP, not only on the IP Address, but also on the DNS Side, and set it to DHCP, if they are not.

I have the first part nailed down, It's fairly easy:
$adapters=$(Get-NetAdapter -Physical |Where {$_.MediaType -eq "802.3"})
foreach ($adapter in $adapters){
    if ( -not $(Get-NetIPInterface -InterfaceIndex $($adapter.ifIndex) -AddressFamily IPv4).Dhcp -eq "Enabled"){
        Set-NetIPInterface -InterfaceIndex $($adapter.ifIndex) -Dhcp Enabled
        Set-DnsClientServerAddress -InterfaceIndex $($adapter.ifIndex) -ResetServerAddresses
    }
}

Open in new window


That part was fairly easy to figure out.
The DNS part eludes me.
I can get the DNS Server address that is assigned to the interface like so:
Get-DnsClientServerAddress -InterfaceIndex $($adapter.ifIndex)

Open in new window


But I have no way of knowing if it was assigned via DHCP or not, even if I use the |fl switch to see all possible attributes, all I get is this:
InterfaceAlias  : Ethernet

InterfaceIndex  : 12
AddressFamily   : IPv4
ServerAddresses : {192.168.81.201}

InterfaceAlias  : Ethernet
InterfaceIndex  : 12
AddressFamily   : IPv6
ServerAddresses : {}

Any Ideas?
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We have total 7 scope configured in DHCP out of which 3 is showing blue exclamatory mark, when I click on display statistics for these 3 scopes all value is showing zero only. Event logs showing error messages like "DHCP client request from C42F909FAB66 was dropped since the applicable IP address ranges in scope/superscope VLAN40 are out of available IP addresses. This could be because of IP address ranges of a policy being out of available IP addresses." for all these 3 scopes only. However all these scopes are not more that 50% occupied.

DHCP lease is 10 hours for all scopes except scope for mobile user.

In DHCP properties DNS Tab
""Dynamically update DNS record only if requested by the DHCP clients"" is checked.
""Discard A and PTR records when lease is deleted"" is also checked.

Assign IP addresses dynamically to clients of: is DHCP

In DNS Scavenge stale resource records are set as No-refresh interval 3 days and Refresh interval 4 days for all the zones and scavenging Period is 1 Day.

I performed the reconciliation and restarted the DHCP services in both DC and is ADC. Also I checked by restarting our ADC as it was also showing the same thing but it also doesn't work however I have not cheeked  by restarting our DC yet.

Please suggest if anyone having the solution for this.
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I have 3 building that are using DHCP on my sonic wall.  I wanted to setup a dedicated DHCP server in the network 192.168.0.5.  I have gotten it to work great for the 192.168.0.X range.
I have a connection going to another building that is using IP address's of 192.168.30.X.  When I use the DHCP on the Sonic wall it works (I did not setup the sonic wall)  I setup a new scope on my DHCP server for 192.168.0 and 192.168.30, I disabled the DHCP on the SONICWALL and thought it would be able find the DHCP server in the subnet of 192.168.30, but none of those devices are seeing it.  That mean I missed a setting on the Sonic wall that routes DHCP to thew subnet for 192.168.0.  If possible can I get some assistance in this configuration?
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AD Box in EC2 , AWS VPC.   1 DC and about 5 Members.   _MSCDS

Error when running DC DIag.

Testing server: \EC2AMAZ-XYZ
      Starting test: Connectivity
         The host 56789e91-a5fe-4d05-8c0d-698f5d2c9330._msdc.domaint.local could not be resolved to an
         IP address.  Check the DNS server, DHCP, server name, etc
         Although the Guid DNS name

         (56789e91-a5fe-4d05-8c0d-698f5d2c9330._msdcs.domain.local) couldn't

         be resolved, the server name (EC2AMAZ-9G30JPN.domain.local) resolved

         to the IP address (10.x.y.169) and was pingable.  Check that the IP

         address is registered correctly with the DNS server.
         ......................... EC2AMAZ-XYZ failed test Connectivity

Doing primary tests
   
   Testing server: IRON\EC2AMAZ-9G30JPN
      Skipping all tests, because server EC2AMAZ-9G30JPN is
      not responding to directory service requests
   
   Running partition tests on : ForestDnsZones
      Starting test: CrossRefValidation
         ......................... ForestDnsZones passed test CrossRefValidation
      Starting test: CheckSDRefDom
         ......................... ForestDnsZones passed test CheckSDRefDom
   
   Running partition tests on : DomainDnsZones
      Starting test: CrossRefValidation
         ......................... DomainDnsZones passed test CrossRefValidation
      Starting test: CheckSDRefDom
         ......................... DomainDnsZones passed test …
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Hello all,

I have DHCP set up to update DNS and discard host A and PTR records after the DHCP lease has expired (without scavenging enabled)  I was wondering if there was a way to "set" how frequently DHCP removes the records?  I can see that the DHCPsrvlog is generating around 12:00 a.m daily and can see it is removing records but I am not able to see when this is happening.  When I test I turn on a client and I can see the dhcp lease and the records in forward and reverse lookup.  Then the lease expires and is deleted but the records stay for X amount of hours, I come in in the morning and they are removed.  Is there a process or event that runs that I can track?  Please remember that this is working without scavenging enabled.

Thank you

Server 2012 r2
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This issue just happened recently. I have several users' desktops having issue getting a DHCP IP address. The strange thing is it only happens on the desktops. I have no problem with a laptop plugged into the switch port. I did a Wireshark captured and it did not show anything interesting. The only thing it showed was the DHCP discovery from the desktop. Any ideas what could cause this?

 

PS. I have port security configured on my Catalyst 4503. But even with port security disabled, the desktops still could not get a DHCP IP address.

 

Thanks
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I am trying to pull down an image from our Windows deployment server to laptops we have here onsite. The laptops are dell latitude 7940s and their network adapters are Intel I219-LM's. When I try to boot into the windows 10 .wim boot file we have on our WDS server I get the error below:

"WdsClient: An error occurred while obtaining an IP address from the DHCP server. please check to ensure there is an operational DHCP server on this network segment"

we have an active DHCP server role on the WDS server which has been able to assign ip address to windows 10 machines I have previously imaged with no issues,

i have tried looking for the necessary network adapter drivers to add to our current .wim file for this adapter but every driver package i downloaded from the dell site will not successfully add to the windows 10 .wim image.


can anyone please advise?
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Years ago I had an employee plugin a rogue DHCP server
into their wallport that caused some clients to obtain
the wrong DNS settings/etc since clients just found the
"first available DHCP server"

Does 802.1x eliminates rogue DHCP servers on HARDWIRED clients ?

If not, what can in a Windows 2016 domain ?
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Hello Everyone,

For configure Failover function reason, I have two DHCP server (installed on Windows 2012 std). I configured DHCP-01 in Active mode and DHCP-02 on Standby mode.
Performing test: All function working well EXCEPT  Reservations section was NOT synchronized between two DHCP server.
If i created reservation on DHCP-01 then nothing record on DHCP-02 and all things the same for reservation on DHCP-02. Even thought Client could obtain right IP but i'd like to the reason why ?
I don't know that is problem or design default on Windows.?
Any one can let me know this issue ?

Thank you for your help.
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Hi all,
I have a 4 DHCP servers in my set-up,
configure by diffent static IP address, static subnets and with different scopes.
however I would like to import all the data in CSV report format at a time
like
1 static ips list with hostname
2 static subnets

have any scripts to run and get all the data at a time.

could you please help me on this


Regards,
MD
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In a virtual environment running Hyper-V I've set up a single Server 2016 Domain Controller running AD services, DHCP and DNS. I then have another member server running Server 2016 for WDS and MDT. During the configuration of the WDS I selected the option for Standalone server. I also have a single VM running Windows 10 and the DHCP service seems to be working OK.  The client is getting the scope options from the DHCP server.

I want to test deploying a Win 10 OS to a test VM using MDT so I built the VM and selected Gen 2 during the creation, but when I try and do a PXE boot I get a message saying:

1. Network Adapter - There was a TFTP error

On my DHCP scope options I have configured option 66 with the IP of my WDS server.

I then created another VM choosing Gen 1 and changed the BIOS setting to boot from the Legacy Network Adapter.  This seems to just do nothing.  I have a black screen with a blinking cursor.  Can any one help me please?

Thank you
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I have a windows 10 computer picking up a suspicious Gateway, DHCP and DNS IP addresses when I do a Ipconfig /all.   What caused me to investigate was the windows 10 computer would lose connection to our mapped network drives.

IP 192.0.0.217
Mask: 255.255.255.0

G.W 192.0.0.194   > should be 192.0.0.254
DHCP: 192.0.0.194  > should be 192.0.0.7

DNS:  208.67.222.220 and 208.67.220.220    > should be 192.0.0.7  192.0.0.10

arp lookup on 192.0.0.194 shows a MAC address for a H.P device.


Any thoughts on this?
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DHCP

10K

Solutions

14K

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).