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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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I am unable to access our Cisco ASA 5505 via ASDM because we don't know IP address. We were setting up the ASA to act as a DHCP server and made a mistake and changed the IP address. We have the credentials to access it via the ASDM but without the password it won't work. I've tried to access it using Putty but it's asking for a password we don't have.  Is there a way to figure out what IP it is set for?
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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 : {}

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

Any Ideas?
Windows 7 Pro logging onto a Windows 2016 domain is very slow - i'm talking 10 minutes or more with the "Welcome" screen. Each user was configured with a roaming profile but I've now reconfigured that by removing the profile link in the user's AD account. I thought roaming profiles was the problem but still the slow logins persist. Nothing much seems to be going on while it's at the welcome screen, it just seems to be waiting for something.
Any clues on what could be causing this please?
It's a simple setup, Windows 2016 DC running DHCP and DNS and a bunch of PCs running Windows 7 Pro. DHCP is set to issue DNS of and
We have had a lot of people in & out of company lately, and can expect a lot more of this over the next month or so, causing my DHCP pool of addresses to be eaten up rather quickly.
I've added more, decreased the lease time from 8 days to 3, but is there a way to revoke(?) any addresses that haven been inactive in the last 3 days?
Also, I had noticed several that had BAD ADDRESS next to them. What's up with that?
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.
I have 3 building that are using DHCP on my sonic wall.  I wanted to setup a dedicated DHCP server in the network  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?
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 …
Greeting Experts,

I need help setting up a PowerShell script to collect all of the Mac address currently blocked in DHCP ( i.e., Mac Filtering). My organization has some DHCP Server (over 60) located at each one of our sites. Can somebody help me create a script to query my companies Domain ( i.e., all the DHCP servers) and come back with a list of filtered mac addresses?  Can somebody help me with this task.... thanks
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
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.


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Merge/Consolidate DHCP scope from on 2008 R2 server into the scope of another 2008 R2 server

Hoping someone who has done this on 2008 R2 can shed some light on the process.
I want to merge several DHCP scopes from an existing 2008 R2 server into the DHCP of another 2008 R2 server without causing any issue to any of them.
Both 2008 R2 servers are currently serving as DHCP servers, but for different scopes on either of them and none of them are shared between them.
The scopes are all different so I am assuming a backup on the source server and import into the target server ought to do the trick.
Or do I export individual scopes and then import then individually?
The scopes do have some reservations so those would have to move as well.
Does the source DHCP server need to be de-authorized, before I import its scope information into the new one?
As always many thanks in advance for insights.
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?
I'm trying to connect a Watchguard T30 to an AP320 through a Cisco Catalyst 2960.

I'm able to set up trunking on the Cisco so that I can see the AP320 through the controller, however when I connect to the WLAN I get no DHCP address, and I can't get online even when I hard code the IP. Based on some logging information I've seen on the Watchguard, it almost looks as though the Cisco switch is sending packets to the wrong gateway address.

It looks like when a device was requesting an IP on the VLAN subnet that request was sent to the lan gateway.

I'm extremely new to Cisco so it's entirely possible I'm missing something obvious, but when the VLAN's are set up on the router and then trunking is configured for those VLAN's on the Cisco, is there a place where you need to specify what Gateway to use for each trunk?
i just want to understand 1 thing

i see a citrix environment in one company

90% of users are using xenapp having non persistence desktops.

i see seperate DHCP scope defined in one of citrix servers.

when i do ipconfig, i see address coming as 10.x.x.x

we have on premise AD where users are synced through AAD sync to office 365 and mailboxes in office 365

outlook is 2010 and is configured on premise in stalled on xenapp and published to studio

my question:
there is group policy called outlook GPO for outlook users whose cache files shoudl be enabled

i know this is bit vague

but if DHCP scope is defined in citrix server and dekstops are getting IP'S from there

how come group policy called outlook GPO is working for outlook users

when there is no DHCP scope defined in AD

I MEAN HOW that GOP is geeting affected in outlook where citrix has its own DHCP

is that some thing AD has in its users and computers accounts for cirtix servers and then it si working?
I have a 4 machines, all running windows 7 pro. They are all on the same domain connected to a server. The server acts as our domain controller and also our DNS server. A router handles our DHCP.

I have 2 machines that are intermittently dropping server connectivity. These two machines will be referred to as 1 and 2.

Machines 3 and 4 have no connectivity issues whatsoever.

Machines 1 and 2 will work all day and then come morning, they don't have access to the mapped drives on the server.

Once they are restarted they connect back and everything seems good.

I have checked both DNS and DHCP settings on all 4 PC's and they're identitcal. DHCP seems to be working as I can release and renew IP's on all 4 machines, and I also checked the DNS by pinging IP's outside the network and also by their FQDN's. (google and bing)

Any ideas why machines 1 and 2 could be losing connectivity?
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 ?
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.
Dear Experts,

 We are setting up a Site2Site VPN between Meraki Firewall MX64W and an ASA 5510 firewall.

First time I do this.

I am not sure how to add the Meraki network peer address in the ASA firewall. All the VPNs I have here are pointing to public static IP addresses. The Meraki is DHCP. I only see that dashboard address that I wonder if I could use.

Any useful documents you know of for this task?

Thank you
Hello I created a new DHCP server and now it pulls multiple bad IP addresses inside the address lease. Can you please help assist why it would pull multiple bad IP address for one device aka phone, computer.
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I have a Mikrotik CCR 1009-8G 1S-1S+ and 5 Cisco Switches WS-C2960-24TC-L that were provided by the customer for our use in this network. I have a question on how to setup the VLANS so no Tenant in the building can access any other Tenants network. There is a mix of Static IP tenants and DHCP Tenants. I have the Mikrotik Setup with all the needed VLANS for each DHCP Tenant. I have also assigned each port for VLAN access to only one Tenant. My issue is how to secure the VLANS.

I know this is a vague description of what I have to work with so I have attached a PDF of the network. If any other information is needed please message me and I will attempt to comply.

Thanks in advance for any and all help.

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
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

Hello Experts,

I am trying to design WLAN solution in open facility, due to cabling\connectivity issue following proposal is provided:

Assume a lager circular facility and outdoor APs (around 120 aps) need to be installed at peripheral.

 we don't have POE option and to install multiple switches thus I need to validate following solution will work?

1.  run fiber across the periphery.
2. connect fiber end to Switch and trunk it with vlan 10, define dhcp scope for vlan 10
3. splice fiber across the periphery at AP connectivity point.
4. use fiber to Ethernet converters.
5. we can use external power injectors.

would appreciate your help in validation.

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
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.


G.W   > should be
DHCP:  > should be

DNS: and    > should be

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

Any thoughts on this?
I have mikrotik 951
I have internet router with ip  and the mikrotik ip Is I add a route to with pref also i have dhcp server on that give the client getaway and dns  as to point it to mikrotik.
till now the internet work on the client without any problem.
when i try to add a hotspot the internet stoped , the client login but no internet.
please note that i setup the hotsport from wizard. and also i disabled the dhcp server after that
so where is the problem ?

DHCPSponsored by ConnectWise





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).