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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We just had an Aiphone IX system installed.   We assigned static IPs to all the devices.   We have a Samsung tablet and phone that we use to control the gates or speak to people when they push the intercom.

I have verified that the tablet and phone are set to Static.  Every day each of those devices changes the IP address.  We set it in the morning and later in the day they get a new IP.

Note:   Our DHCP has a scope of 50-200.   The IPs we have assigned are above 200.   One suggestion that we have not tried yet is to create a Reservation for those two devices.  Any thoughts on this?

I have discussed this with 4 technicians and all of them state that if an IP is assigned as static it can only be changed manually.  

We have been researching this with the company that installed it and with Aiphone.  No one can figure this out.

So my question is how is it possible for the IPs to be changing?   I know that it is not being done by anyone.   The devices are turned on in the morning and just sit on the desk until someone comes to the door or pushes the intercom.   Any ideas will be appreciated.
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Hi experts,

here I use SCCM with several DPs in several locations.
My question is, in one location I have a LINUX DHCP server.
To configure PXE, what kind of DHCP options I have to use on the LINUX DHCP to reach the WIndows SCCM PXE Server ?
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Good day, long post ahead, help needed!

We help a shelter that is having major connectivity problems. Here is the situation.

In the spring, we had to perform a hard reset on each AP. Unfortunately, the controller was lost in a computer swap out before we came to assist this building. We recreated the networks, and ever since, they have been having terrible connectivity on their devices. On average, every day 3-4 devices cannot connect. Usually the message is 'Cannot connect to network' or similar. Sometimes they connect, but then have no access to internet. They will 'forget' the network, and maybe 50% of the time it works. Sometimes they just leave the phone, and a few hours go by and it works again. Extremely inconsistent. The experience score is low, usually around 50-60%.

The building is on 3 levels. There are 3 on the main floor, 2 on each upper floor. They are all installed in central locations in hallways on the ceiling. They are all UAP-AC-Lite Access points, powered by a US-8-150W.

When I am onsite, my devices connect with no problem, signal strength is good too. But they constantly are having issues, and I am getting desperate for help. An important thing to note is that there was NO connectivity issues before we reconfigured the access points.

Here is what I have tried:

Removing/re-configuring all the wifi networks.
Manually set the 2.4G channels to either 1, 6, or 11, hoping they wouldn't interfere.
Daily reboots of APs
Configure DTIM to 3/3
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We are going to upgrade the DHCP server to Server 2016 or 2019.
Requirements:
1. DHCP service failover or HA
2. Multiple vLAN via core switches

Any ideas which version should we use? Any new features on server 2019 on DHCP service?
Thank you.
Existing Environment:
A Cisco Switch worked as DHCP replay, Two DHCP servers for failover. (2003 or 2008)
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Hey there Experts!

I'm running into a frustrating issues with being unable to update DHCP DNS server on CISCO ASA via SSH.
Logging into the ASA we're processing the following CLI CMDS:

ASA-Hostname: Enable
(successful authentication)
ASA-Hostname# dhcpd dns (dns server needed here)

Unfortuantely we're getting an error thrown at the d in the dhcpd command.
I apologize if this is too simple of a question. I tend to avoid Cisco like the plague and maybe I'm missing a step here.
Researching online the DHCPD CMD seems to be the one that I'm needing.

Your help is appreciated!
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I have been using Netsh to create a back up text file and Database file(db) and automatically copy the results to a server share as follows:
netsh dhcp server dump > \\Server-IP-Address\Sharename$\dhcpcfg.txt
netsh dhcp server export \\Server-IP-Address\Sharename$\dhcpdb all
pause
This worked great with Server 2008 R2 but is not working with Server 2012 R2. Can you please advise me as what the problem and solution might be or another possibly power shell command that might do the same things with the same output?
1
I have a network which currently has the voice and data all on the same network space (192.168.27.1/24). The DHCP server is a Draytek 3900 Series Firewall and the network switch is Catalyst 2960 L series.

I have access to the CLI on Cisco but have zero experience using the command line interface so ideally would be better if we can configure the network switch to allow me to access via a browser (if thats easier for configuring switch).

Any advice on how to achieve this would be appreciated.

Thanks
Sycamore IT
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I have a stand-alone server that is host to a web application.  I've created a new domain (new forest) for security as well as preparing for additional servers.  I have a problem where it looks like dns svr records were not created correctly during the DC Promo operation and now there appears to be connectivity issues.  Dcdiag /fix returns the following error:

   Testing server: Default-First-Site-Name\HOST1
      Starting test: Connectivity
         The host 5c533dbd-a226-42e6-8968-b6c5296c08fe._msdcs.mydomain.com could not be resolved to an IP address.
         Check the DNS server, DHCP, server name, etc.
         Got error while checking LDAP and RPC connectivity. Please check your firewall settings.
         ......................... HOST1 failed test Connectivity

What is the best way to resolve this?
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Currently having a backup issue with a specific backup solution we use by a specific vendor - and the case owner is hung up on a VSS 8193 error that's being logged in the event viewer application log. The error is only logged on a reboot of the server and/or a restart of the "cryptographic" service on the server - is documented to not cause issues with backups - is being logged on every other server we support that do not have issues with backup using this same vendor solution -  and at this point I'm stuck in getting further support until I get this 8193 issue resolved.

Following is the Microsoft article referencing this issue and the fix. The solution involves using a *subinacl* tool to reset a specific VSS registry subkey - back to the correct permissions as set before the key was modified when the DHCP role was configured on the server.

https://support.microsoft.com/en-za/help/2298620/vss-eventid-8193-is-logged-when-you-restart-the-cryptographic-services

I've not used this tool before so want to run this by the experts on this forum to make sure I have this process correctly understood before implementing. This will be implemented on Server 2012 up to Server 2019.

If someone might be able to provide a step-by-step, would be most appreciated - thanks much..

VSS-Error-Snap.PNG
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hello IT fellas

I have a question in Windows DHCP server. Which I have many bad address problem in it. So, the question is:
Is there any command in powershell to delete all the bad addresses at once?
1
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I need to check the communications between a workstation and a dhcp server but without changing the network adapter configuration

Is there a command in powershell or similar?

Thank you.
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I have a 2008R2 DC which is also a DHCP server. I am having an issue where the server keeps running out of IPs in the scope as well as handing out IPs that are already in use even though I have conflict detection enabled as well as a lease time of one day. Don't know what's going on.
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Good day. I have a Data and Voice VLAN, with the PC's getting DHCP from Microsoft DHCP Server (2012) and the phones from a Linux DHCP. I want to decommission the Linux DHCP and move everything to Windows DHCP. Phones are Polycom Soundpoint IP 331, Server is 2012, Voice VLAN ID:2. Please assist to configure phones to get DHCP from Windows server.
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Hi,
I have an issue with my server running Windows Server 2016. I think the issue is DNS or DHCP related but unsure.
for a while now, myself and a few colleagues have been domain joined.
When we're out and about, we connect in to the server Via VPN - which seems to work fine.

The server assigns an IP address and lets us in.

This has stopped working now and I can't figure out what config has changed.

If I connect directly to the network where the server is at, my laptop gets no internet at all - when I try and troubleshoot I get an error which says "WiFi" doesn't have a valid IP configuration. The IPv4 settings are set to retrieve the settings automatically from the DHCP.

Interestingly, I am trying to connect a brand new laptop up to the domain and having a slightly different issue. When the new laptop is on the same network, the servers DHCP manages to assign an IP address. When I go to join the domain, it asks for credentials but then errors and says:
The following error occurred attempting to join the domain "xxxx.local" The network path was not found

From this new computer, I can remote desktop into the server when I disable the server firewall- even though it isn't domain joined
and with my existing computer, which is domain joined, I can't RDP in now.

Both new and old laptops are on windows 10 pro - the oldest being less than a year.

Any help would be hugely appreciated

Kind Regards,
Dave
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Hey all,

Is it possible to locate and find the above switch on a network? I dont have the cisco cable which allows to connect via the admin port on the back of the switch and Im wondering if its accessible via a web browser session? I dont know the IP address of the switch thou, would it pick up one via our dhcp server or is there a way of searching for the switch using a tool?
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I have a Server running Server 2008 R2 Standard and a Sonicwall TZ500. I setup a DHCP Scope on the server to be 192.168.100.13 - 100 and on the Sonicwall 192.168.100.101 - 254. The problem im having is that the server will run out of IPs and the Sonicwall wont take over. Im not sure if i need to enable IP helper on the sonicwall. Does anyone have experience with this type of setup.
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I have just installed a new network with one server, configured as a domain controller running Windows Server 2019 and about 10 workstations running either Windows 10 or Windows 7.  This is something that I have done successfully numerous times.  However, this one is causing me problems as computers are not getting IP addresses or DNS from the DHCP server and even when they are given static IP and DNS, they do not get Group Policies, for example, mapped drives or folder redirection.  Even those PC’s that have been given static IP and DNS still can’t reach every web site, including their own. Roaming Profiles do appear to be working.
On one PC that was showing an IP that may have been setup statically by the owner (who was away so I couldn’t ask him) I flushed the DNS and released the IP address and re-booted the computer.  It failed to get any IP.

There was a previous server that was in use prior to the company moving to new premises and we were instructed to use the same domain name.  Each workstation was taken off the domain by making it join a Workgroup and was then joined to the new domain (of the same name).  However, this was only possible with static IP, etc.  All the workstations are now members of the new domain.

The old server had started to develop problems before the office move and is inaccessible.

Server has a static IP: 192.168.11.10
Default Gateway (the router): 192.168.11.1
DNS: 192.168.11.10

DHCP has been setup with a scope of 192.168.11.2 – …
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I upgraded a 2008 R2 Datacenter server functioning as a domain controller and DHCP server. I upgraded to 2012 R2 Datacenter. I made it a replica domain controller with DNS and made it a Global Catalogue server and then installed the DHCP server role. I backed up the DHCP database on the 2008 server, copied the file to the new 2012 server and I believe I successfully imported the dhcp database file. I have done this many times. All the scope settings, reservations, lease, etc. showed.
I went to authorize the new server and it says it’s authorized under manage authorized servers but will not issue IP addresses.
When I select IPv4 or Scope within the console, it says the server needs to be authorized.
I have installed and uninstalled everything several times but end up with the same result = no ips being issued.
Suggestions please ????
0
I have a 2016 WDS (with ADK, WinPE, MDT) server fully installed with all the required and appropriate components (newest versions) and working now.

DHCP is working (on different server with option 66 defined - WDS server name/IP) as I can see the server when I PXE boot one of our HP desktops.

I managed to upload an .iso of W10 1903 to the WDS server, create boot and install images without issue.

I then booted an HP desktop to PXE, found the WDS server, authorized the PC (I set that option) and successfully downloaded W10 1903 unto the PC without issues.
Note that I deleted al 4 partitions on that PC when it prompted me re. drives and created one single large partition. I believe W10 then automatically makes additional partitions as needed as I did not make them and they were there later.
I completed the setup and played with the o/s and it worked without issues.

After that worked I went through the process again with drives being formatted and a single partition (about 450 GB) being made, but this time I did not complete the setup, rather I entered Audit mode at first opportunity (language selection screen) through Ctrl/Shift/F3.
This also worked without problems and I managed to install Office 2013, as well as a few other smaller applications. Various Windows updates were also installed and it always rebooted back into Audit mode as expected.
After it was done I did a sysprep (with Generalize) and shut down the system.

Then I went back to the WDS server …
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Hello Experts,

Good day to you all!

I am not well versed with Cisco equipment but know a little bit with networking, that's why I decided to learn Packet Tracer. So, I was following a video online that simulates an internet connection configuration. I followed the video and recreate the Packet Tracer file and after I was done, everything was working. A workstation was able to access the simulated internet setup.

Now, I modified the setup from the example in the video to be a little bit close to what I have in the office. I added an ASA 5505 in between the Modem and Router 1841.

That's where my challenge started. I cannot for some reason, find out how make ASA work together with the rest of the set up.

I was hoping somebody here would be able to help what am I doing wrong.

I am also not sure what to attach or post here, to help you guys troubleshoot. I'm starting with a diagram and the configuration files of the ASA and Routers, and please let me know if there's anything else you need to help me out troubleshoot challenge i have.

Thank you in advance!

Regards,
BASTi

P.S. - I forgot to mention, I tried changing the type of cable connection from "straight-through" to "cross-over", between the modem and the ASA, and there's no difference.

ASA 5505 Packet Tracer Simulated Internet Connection
-------
ISP Router 1841 - Running Config
-------

version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
0
My DHCP server tree does not expand.  See screenshot.  I have been having an issue adding a static ip address to a computer as well.  Any ideas for this issue?  It has never done this since I set it up 6 years ago.    Windows Server 2008 R2
Screen-Shot-2019-08-29-at-11.53.05-A.png
0
Given Below:
VLAN8   Server
VLAN16  Users
VLAN32  VOIP
VLAN64  Staff-Wifi
VLAN128 Guest-WiFi


We are facing issue for the DHCP distribution,Currently SW port 25,26 and connected Hyper-V host1 and SW port 27,28(Cluster1) connected to Hyper-V host2(Cluster1),
Please help to see anythong was wrong in the configuration .I try in Cisco Switch i just configure sw port to access mode VLAN 8 .But i not too sure why they configure like below:

member 1 8    ! N2048
exit
ip route 0.0.0.0 0.0.0.0 10.65.8.254
interface vlan 1
ip address dhcp
exit
interface vlan 8
ip address 10.65.8.201 255.255.255.0
exit
interface vlan 16
ip helper-address 10.65.8.61
exit



interface Gi1/0/25
channel-group 5 mode active
switchport voice detect auto
switchport mode general
switchport general pvid 8
switchport general allowed vlan add 8
switchport trunk native vlan 8
exit
!
interface Gi1/0/26
channel-group 5 mode active
switchport voice detect auto
switchport mode general
switchport general pvid 8
switchport general allowed vlan add 8
switchport trunk native vlan 8
exit
!
interface Gi1/0/27
channel-group 6 mode active
switchport voice detect auto
switchport mode general
switchport general pvid 8
switchport general allowed vlan add 8
switchport trunk native vlan 8
exit
!

interface port-channel 5
switchport voice detect auto
switchport mode trunk
switchport general pvid 8
switchport trunk native vlan 8
exit
!
interface port-channel 6
0
Not sure what I'm doing wrong in trying to setup an ip address on a win 7 pro laptop.  I am trying to change the ipv4 settings from "obatain auto" to an ip address I specify.  I have done this before and it has worked.  When I enter the info and exit it says that DHCP is not enabled and then the settings go back to auto obtain.  Any ideas?
0
I had this question after viewing Can Ping Gateway but NOT DNS Server.

A client of mine has this same issue. The fix in "Can Ping Gateway but NOT DNS Server" did not work. I have applied all of the fix items noted in that thread, including the fix solution.

Some data:

Four computers in this office are just fine. They can ping the gateway located at 192.168.16.1. They can ping the DHCP Server located at 192.168.16.3. They can ping the DHS Server located at 192.168.16.3. I have attached the results of an ipconfig /all command here as the file ipconfig.good.txt.

One computer is having problems. It can ping the gateway at 192.168.16.1, but CANNOT ping the DHCP Server and DNS Server at 192.168.16.3. I have attached the results of an ipconfig /all command here as the file ipconfig.bad.txt

The problem happened out of the blue yesterday afternoon. The Windows error logs show no suspicious events during that time period. The machine has a clean registry and clean malware status.

All ideas invited.

-- stan

- - - - - -
Stanley Krute
Chief Technologist
Siskiyou Digital Inc.
stan@siskiyoudigital.com
530-905-0099
ipconfig.good.txt
ipconfig.bad.txt
0
Team,

I have a WDS set up on my network.
It is not on the same server as the DHCP.

I am not seeing option 60 appearing in my DHCP scope options.
Also, how do i get WDS to be discoverable across multiple subnets?
Is there anything for my network team to configure?
We already have ip helper-address configured to point the different subnets to the DHCP server.
0

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).

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