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 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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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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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.
0
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 ????
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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
!
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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
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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?
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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
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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.
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Hi,

I just want to clarify something about scavenging and dhcp lease time. Does the scavenging Refresh and No Refresh settings have to be equal/or less than the dhcp lease time or does the scavenging period have to be equal/or less to the dhcp lease time? For example if my dhcp lease time is 4 days then should refresh and no refresh period be at most two days a piece? What should the scavenging period be for this amount of time, does it matter?

Thank you.
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Say, I have a Ethernet IP camera connected to a Billion router and wish to create a wireless link to a second Billion router which connects to the network. I believe I have created "WPS connection" between the 2 devices. I'm unable to ping the IP camera. The configuration is as follows: IP camera has a fixed IP address on the range 192.168.1.0 /24. The 2 Billion devices each have unique IP addresses on the same range.
The Billion devices are as follows: An older device. The EIPAC BiPack 7300 NX. DHCP has been disabled on this device. A Billion Wireless-N product, model number BIPAC 3100 SN Ethrnet Access point. I would imagine it's something small that I'm doing incorrectly.
The network that these devices are connected to, is also on the same IP Range as above. There is no IP address conflict to my knowledge.
Please describe the basic principles. Kindly describe an alternate method to using the WPS system. It might be simpler if I configure some manual authentication process.  The overall set up is the one Billion device and the camera would be mounted at the inspection point, at the surveillance and the second Billion device would be connected  into the network. Currently I have tested all the devices at short range but to no avail.  Your assistance will be appreciated.
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I am implementing an Aironet deployment, and I am not sure if I am seeing unnatural instability... or if these things just "do" this sort of thing. My infrastructure is solid, and I am using two subnets- 192.168.1.0/24 and 192.168.3.0/24. My wireless devices will all exist on the 192.168.3.0/24 subnet, so the access points are plugged in there, and I have also connected two of the ports on the WLC 3504 to the 192.168.3.0/24 subnet. I have also connected the service port on our 192.168.1.0/24 subnet, for a number of reasons I won't go into now. There is no DHCP server on the 192.168.1.0/24 subnet, but there is one on 192.168.3.0/24, and the subnets are physically connected via Cisco 2901 router. The service port is configured at 192.168.1.68 and the two other ports are statically set 192.168.3.68 and 192.168.3.69. Just letting things sit, I noticed the SSID's keep appearing and disappearing every few minutes and I consoled in to the AP to see this cycle:

[*08/13/2019 18:50:24.7198] AP has joined controller USMDWLC00
[*08/13/2019 18:50:24.7698] DOT11_DRV[0]: Stop Radio0
[*08/13/2019 18:50:24.7798] DOT11_DRV[0]: Start Radio0
[*08/13/2019 18:50:25.9294] DOT11_DRV[1]: Stop Radio1
[*08/13/2019 18:50:25.9394] DOT11_DRV[1]: Start Radio1
[*08/13/2019 18:50:27.3889] Password for user changed
[*08/13/2019 18:50:27.5989] save_on_failure is set to 1
[*08/13/2019 18:50:27.5989] save_on_failure is set to 1
[*08/13/2019 18:52:08.6904] Re-Tx Count=1, Max Re-Tx Value=5, …
0
Current Configuration:

Three DCs:
DC01 Running Server 2016 Standard, running AD, DNS, WINS
DC02 running Server 2012 R2, running AD, DNS, WINS and DHCP fail-over from DC03.
DC03 running Server 2012 R2, running AD, DNS, WINS, and DHCP with fail-over to DC02, and all FSMO roles
NAS containing User's Data and Roaming Profiles, redirected via GPO's. Some Public data is stored on DC01.
33 Users
4 User PC's - All users are required to have access all four PC's (hot desking).

All replication works fine for AD, DNS and WINS, as does the DHCP fail-over.

I need to update the whole network to native Windows Server 2016 Standard, or better still 2019, without turning the above servers into doorstops, and with the minimum of downtime.
At the end of this exercise, DC02 will be removed from the network completely, as it is not upgradeable, and will only run 2012 R2.
DC03 will also be removed from the network, but will have the Motherboard upgraded, and the system rebuilt as Server 2016 Standard or preferably 2019 Standard.

Can I do it like this?

01 Move all of the FSMO rolls from DC03 to DC01. This would make DC01 the Primary controller.
02 Remove DHCP from DC02 and DC03, and put it on DC01. Break the fail-over between the DC01 and DC02, and then add the DHCP role to DC01. Finally, do backup of DHCP from DC03, and then restore on to DC01.
03 Remove DNS, and WINS from servers DC02 and DC03, leaving DC01 as the only server running DNS and WINS.
04 Demote DC02 and …
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We have two Cisco 5508X firewalls (one is for failover).  For VPN, we use the old Cisco VPN Client (5.7) and IPSEC.  In the configuration of the firewall, clients authenticate against the domain controller’s address.  The domain controller’s OS is MS Server 2016 Datacenter.

We have noticed in DNS (Microsoft) that some of the VPN clients have the same IP addresses.  There is not a DHCP scope (Microsoft) setup for the VPN network.  To ensure that each VPN client has a separate IP address, can I simply create the scope in DHCP (Microsoft), or is there more to it?
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Have an HP Color LaserJet CP4025.

Believe the NIC card is bad but have not proven it to my complete satisfaction.

As I am nervous Ned, I want to be sure before the boss brings in the Printer Guy at $150 an hour and proves me the fool.

Printer lost connectivity to the switch.

Checked all the patch cables from the printer, through the wall, to the switch.

All good.

Checked the config on the switch.

All good.

Used other ports on the switch.

All good.

Still no connectivity.

Tried to connect an RJ45 cable from a computer NIC to the printer NIC.

The printer does not show any default 169 do IP address.

The JetDirect menu choice from the printer display is missing meaning I cannot set DHCP.

Did a factory reset.

Did a cold reset.

No go.

Should I grab a laptop and a serial cable and give it a go, or has Nervious Ned done everything he can do to prove the NIC is bad?
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Dear Experts, we are configuring a new network of new office in next week and have some questions about security:

- How to prevent "rogue" DHCP servers in network?
- How to prevent "rogue" Wireless Access Point in the network? For example: my office's wifi network is "ABC.com" => we'd like to prevent the other SSID "ABC.com" from users' APs?
- Can we prevent ransonware in some network levels?

Our infrastructure is:
- 2 x Firewall Sophos XG310
- 2 x Core switch Cisco 3850 (will be DHCP servers for 20 VLANs)
- 30 x Access switch Cisco SG220 and SG350
- 30 x Wireless Access point Unify AC AP PRO
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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).