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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I have a DHCP server with two IP scopes.  We also have VOIP phones that use a separate VLan and receives their IP addresses via a DHCP server on my router.  We had some problems with the VOIP Vlan and was forced to put all the phones onto the default DHCP server with my computer devices.  Once we fixed the VLAN issue, we changed the configuration in the phone which put all the phones back on their own VLAN, thus releasing all the IP's leases from my default DHCP server.  This morning, I got a warning that my DHCP server was using 88% of the IP's, looked at the server and all the phones leases were back.  I know these phones are not using these IP's because the change is manual.  Each phone had to be put back onto their VLan through a manual setup.

My lease time is 6 hours, so I deleted all the phone devices that showed up, but does anyone know why after a week, they showed up and started pulling IPs?
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Windows Server 2016 DHCP server stopped handing out IP addresses.  I'm receiving a ton of the following error in the event viewer:

  • PTR record registration faor IPv4 address [x.x.x.x] and FQDN [computer name] failed with error 9017 (DNS bad key)
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I want to setup a single scope to hand out addresses to all of my student laptops....640+ laptops.

Using Windows 2008r2 server.

Is that possible?  

Thanks!
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We currently have 13 Access Points controlled by a Cisco WLC 2504.  We have two WLans - one for Guest and one for employees.  Our employees use WLan 1 which accesses the DHCP server on my domain.  The Guest uses WLAN 2 which access the DHCP on my router.  On my DHCP server we have two separate subnets with plenty of IP's available.  Due to some routing issues, I needed to use most of the available IP's for phones.  Once that was cleared up, those IP's are now free again.  My problem is that we are now unable to get an IPV4 address from the employee access point.   We have two subnets, so there are plenty.  What do I need to do to fix this issue.  Interesting enough when I create a separate vlan pn my router, any device connected to the employee access points gives me the error message - no internet access
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I'm currently replacing (NOT migrating) an old Windows 2003 SBS server (running AD,DNS, DHCP & File Sharing) with a new 2016 Essentials server.  The current 2003 SBS server is currently only server on the network with about 5 users, so it's a small implementation.   Email has been moved to O365 so nothing needs to be done with mail services.

Since the 2003 AD is cluttered with junk from over the years, I'd like to setup the new 2016 server with a completely new domain and NOT joining it to their existing 2003 domain. I'll setup the DHCP & DNS configurations, and the few users and shares can be added from scratch on the new server, then unjoin the workstations from the old domain and join them to the new domain.  

Also, after the new server is on the network and the workstations are joined to the new domain, I'd like to keep the old server on the network so I can copy some files to the new server.

I understand that since the old server is running DHCP & DNS, I'll have to turn those services OFF on the old server once the new server is on the network and handling those services.  I'm sure there are other caveats that I'm not thinking about.  

Has anyone done this type of server replacement (NOT a migration), and if so, can you provide any information or "gotchas" that I need to watch for?

Thank you.
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I have installed a new firewall and changed the gateway IP in the process for a small network. now that it is different, i added the new ip in DNS and changed it in DHCP in my server. for some reason, i am not able to access my sonicwall from my server. i can not ping it or get to it from the web browser. the other devices on my network can get to it just fine and are all on the same switch. i put in a new switch because there was a bad port on the old one, thinking it was just a switching issue. i have disabled my firewall and all the antviruses on my server and still cannot connect. my dns is not functioning correctly because of this as well. any ideas? Im at a loss
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I have a Server Essentials 2016 installed. DNS is installed. DHCP is installed and a scope is setup. the router is set as the gateway. I turn DHCP off on the router intending for the server to handle this but I am missing a piece(s) of the puzzle because it doesn't work. This is a test setup and I am using a home router for learning purposes.
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We have a DHCP server with multiple scopes (VLANs). We have option configured for VoIP phones too. It seems to be straight forward to configure as per MS, but anything can happen while we try to configure!. Any of you had any problem of making to work?.  Do we have to do anything on the network equipments to make this work?
I am looking for EE/KB article . I would appreciate if you could help me on this.
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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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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 192.168.5.3 and 8.8.8.8
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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?
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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
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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.
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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 192.168.5.1/24 subnet that request was sent to the lan 192.168.1.1 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?
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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?
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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?
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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
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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.

Seven-Floor-Multi-Tenant-Building-De.pdf
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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.

TIA
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hello experts
i need via command to configure my window 2008 R2 DHCP server option 121, but i got the following error so it not works, could you help on this how to do this correctly?
thank you

C:\Windows\system32>netsh dhcp server 10.137.22.36 scope 10.137.25.0 set optionvalue 121 binary -NetworkAddress 1.1.1.1 -SubnetMask 255.255.255.255 -GatewayAddress 10.137.25.254

Changed the current scope context to 10.137.25.0 scope.

DHCP Server Scope Set OptionValue failed.

Parameter(s) passed are either incomplete or invalid.
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The original IT people started using the 10.0.0.0/24 subnet. I am in the process of migrating to a new server. I set up the DHCP Server with the same scope but when I look at a workstation that received a DHCP address it is telling me the subnet mask is 255.0.0.0 which is not correct. It should be 255.255.255.0 but I can't find anywhere in the DHCP server to set the subnet mask it passes out. Can someone clue me in?
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dhcpconfiguration.txt
Dear Experts

We have a network of less than 15 systems with 2 broadband connections from 2 different ISP's.
1. ISP1 in their provided router configured the network of 192.168.1.0/24 and their provided router ip 192.168.1.17 and function's as DHCP server in the LAN
2.. similarly ISP 2 also configured in their provided router with network of 192.168.1.0/24 and their provided router ip 192.168.1.1 and this also funcationing as DHCP server in the LAN.2
Both the routers of both ISP's are connected to the same switch at the present I have turned off ISP 2 router to avoid 2 DHCP in the LAN.
3. have linux server working as internal private DNS
As per the experts exchange experts advice I am in process of procuring the router with 2WAN port so that each one of the ISP will be connected to one of the WAN port and will stop DHCP service on the router level and will configure DHCP server in linux server. I would like to divide the network of 192.168.1.0/24 to 4 subnets, as following
a)192.168.1.0  of ip range 1 to 62
b)192.168.1.64 of ip range 65 to 126
c)192.168.1.128 of ip range 128 to 190
d) 192.168.1.192 of ip range from 193 to 254

attached DHCP configuration, request to please review the defined 2 subnets statements in the config
Soution design and suggestion for the below please:
in this dhcp server the defined 2 subnets i,e access point-1 to one of the subnet of above a) i,e 192.168.1.0  of ip range 1 to 62 and access point-2 to another …
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Hi all,
I would like to reserve an ipadress + add a host name etc on my DHCP server based on a mac address using PowerShell (of course)
Could you help me ?
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Dear Experts

We are in process of setting up very small IT infra where local dns (private dns server) be done on ubuntu server16.4.4.  We will be hosting web based application server in on-premise and for the internet we have 2 service providers  both are of different,
1.  ISP 1 provided device enabled with the dhcp service for the network and it is ON with the subnet of 192.168.1.0/24  this is more stable connection
2. ISP2 also provided device and enabled with DHCP service for the network and they are asking to turn it ON -
purpose of 2 service provider is to have backup when one is down operation can happen with other service provider
As of now I have not yet turned ISP-2 modem/router ON as this will also function as DHCP server and in a network 2 DHCP server cannot be enabled.
Please suggest the best practice
1. Should I have to ask ISP-2 to configure for different subnet like 192.168.70.0/24 and configure one DHCP server in linux server define 2 subnets here and stop both service providers ISP-1 and ISP-2 modem/router DHCP service but when the clients systems boot which subnet to be released as ISP-1 may be down and but the DHCP server release the IP of subnet ISP-1 , how to switch here to another subnet - NOT sure if this is good way to go with please suggest
2. stop dhcp service of ISP-1 and ISP-2 devices and configure dhcp server in linux but with one subnet only but segment the ip range for ISP-1  router and gateway sections pointing to ISP-1 in dhcp …
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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).