53

On one of the affected Windows clients start a packet capture (Wireshark, Microsoft Network Monitor, Microsoft Message Analyzer, etc.), then from an elevated command prompt run ipconfig /release. The DHCP client will send a DHCPRELEASE message to the DHCP server that it obtained it's ip address from. This should allow you to obtain the MAC address of the ...


38

Found it!! It was my DCS-5030L D-Link Network Camera! I have NO idea why this happened. This is how I found it. I changed my laptop IP Address to 10.255.255.150/255.255.255.0/10.255.255.1 and the DNS Server 8.8.8.8 so that it would be in the range of what the rogue dhcp was dishing out. I then did a ipconfig /all to populate the ARP table. Did a arp -a to ...


25

With a very low lease time you will see an increase of network traffic, particularly broadcast traffic as the "discover" and "offer" phases of DHCP are layer 2 broadcasts. How much of an issue this is depends on many factors such as the size and complexity of the network, latency, performance of the DHCP server, etc. Keep in mind DHCP clients do not wait ...


18

Do a binary search. Disconnect half the cables Using '/ipconfig release' test if it's still there If so, disconnect another half of the remaining and goto 2 If not, reconnect the half of the previously disconnected first half, disconnect the second half and goto 2 This will divide the network into two each successive test, so if you have 1,000 machines ...


17

You could just: Open the network and sharing center (either from start or right click the network tray icon), click the blue connection link -> details. find the ipv4 dhcp address (in this example it's 10.10.10.10) Open Command Prompt from the start menu. ping that ip eg ping 10.10.10.10, this forces the computer look up the dhcp server's MAC address and ...


15

Matching the DHCP lease times with the connection limit of your AP doesn't strike me as the best way of handling the issue. The two don't have to match. Lower the DHCP lease time to something like twice the length of the demo (completely arbitrary suggestion) and expand your DHCP scope to accommodate as many leases as you think you'll have in a reasonable ...


12

The network will keep working until your DHCP leases expire. After the leases expire devices may switch to RFC 3927 addresses. But those addresses are not predictable so you'd have to rely on MDNS to find them, and they are unlikely to work between a given pair of devices until both have switched from DHCP assigned addresses to RFC 3927 addresses. On the ...


10

Ip addresses are meaningless without a subnet mask. When you say the scope encompasses the whole 10.2.0.0 range and then say that range is 10.2.0.0-10.2.63.254 you're implying a subnet mask of /18 (255.255.192.0) because that's the only subnet mask that gives you that ip address range, but we wouldn't know that is the subnet mask you're using because you ...


9

Assuming the router is still acting as a DHCP relay and forwarding the request to your original server, then the reason it did that is simply because that Windows DHCP server told it to go ahead and use the IP. In this instance the DHCPNACK from the new server is irrelevant, as a DHCP client will consider all responses, and since it got an offer from the ...


9

As MadHatter mentioned in a comment, the leases file is periodically re-created to avoid this problem. While the period isn't mentioned in the documentation, discussions on the dhcp-users mailinglist indicates that it should be done once an hour, and I've checked the source code and found that this is correct. Unfortunately this isn't a configurable option. ...


9

A DHCP server must have a configured IP address so that it can know which scopes are locally attached to physical interfaces, and which Scopes can only be served via a DHCP relay. Ignore a management point of view, I am sorry, but I think it is silly to try and hand-wave away and ignore the practical issues about running your network. Getting a valid IP ...


8

You can't thru DHCP itself. It doesn't have provisions for this. The only thing you can do is to force the client into a disconnect/reconnect. - Pull the cable. - If the client is on a managed switch to which you have access you can disable/enable the switchport. - If you can login remotely to the client and you have the required authorisations on the ...


7

The FORCERENEW provides the mechanism for the server to indicate to the client to re-new. Not sure if it is implemented in your distro.


7

OK, I have a couple thoughts: There are as many DHCP stacks as there are stars in the sky. OK, not quite, but you get the idea. Embedded networking stacks are especially known for having non-complete "standards" implementation. As such, it's highly likely that your devices will end up booting before your DHCPd is ready, will APIPA, and won't ever retry DHCP....


7

Add the DHCP role to the physical DC. Authorize the DHCP server. Create an appropriate scope with appropriate options. You'll need to create a Scope appropriate for your network with the appropriate Scope options.


6

The spec for option type 6 has variable length and can support more than two entries. The length field is 8 bits and represents the number of bytes. 256 / 4 = 64 IP's. Clearly this is well beyond the number that the client must recognize, but specifying 3 entries is likely supported by many clients. It certainly won't hurt anything. orst-case the client ...


6

The problem is that your client is not talking DHCP but bootp. Not all dhcp servers handle bootp as well due to design limitations or configuration settings.


6

None of the above - you're confusing Lease Time with a DHCP client releasing the address. The client should always renew the IP address well before the lease is up, meaning that there are no problems so long as the client remains active. The only real problem with a short lease from an ISP is that you have no guarantee that you'll get the same IP back if ...


6

IF you really want to you can disable rogue DHCP server detection by setting the REG_DWORD value DisableRogueDetection to 1 under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DHCPServer\Parameters. As an aside: It kinda sounds like you installed the Hamachi adapter directly on the Windows SBS 2003 computer. If that's the case then you're probably ...


6

With much thanks to ErikE and the others here, I've gone down a path...I won't say it's the right path, but the Powershell script I've come up with does the trick. The code is below if anyone wants it. Just run it manually pointing at each DHCP server or schedule it (again pointing to each DHCP server in the script). What the script does: Gets lease ...


6

While product recommendations are off-topic for ServerFault and I expect your question to be closed by the community in short order, I can offer two suggestions: Limiting yourself to a GUI-based system is limiting your ability to implement the best solution for your situation. Perhaps a system with a GUI will work well, or perhaps not. In spite of the above,...


6

There's an official Technet guide for this that I'd use, rather than that one. The process below is a "merge," rather than what would normally be called an "import", and will only modify existing scopes if you import scopes that exist on the target server. If that is the case, you'll need to selectively import scopes, instead of just using the /all switch. ...


6

Here is the Technet DHCP Console Icon Reference Guide. That icon means: DHCP server warning. Available addresses for server scopes are 90 percent or more leased and in use. This means that the server is nearly depleted of available addresses to lease to clients.


6

My understanding of DHCP is, a client broadcasts a DHCP Discovery request on the network, and any device on the network can respond. A client can make an unicast DHCP request too, the renewal request is made in unicast, so the client requests directly the DHCP Server. What if the DHCP changed his original IP address ? The renewal will fail and the next ...


5

Generally a DHCP relay is supposed to pick up a broadcast from a client and forward it to a specific server (read: unicast) address. Given that the packet sent by the relay to the server can be routed anywhere, the idea of cascading relays doesn't make a lot of sense. In practice it would be more likely to have some kind of intermediary DHCP server that ...


5

You need to change the subnet on your computers from a /24 to a /23. 255.255.254.0. On computers that have static addresses, such as your servers, you'll need to do it by hand.


5

Disable the DHCP service of your router.


5

Everything you want to do (but the billing system) can be done by pfsense out of the box. Including load balancing - just add another NIC to your box.


5

What needs corrected or cleaned up with the order of operations? Nothing Is there any AD data (including logs, though their location is usually pretty standard) that I need to clean up from the decommed DHCP servers? No. There's no AD data in the DHCP database, AD data is in the AD database. Will there be any references to the domain account that ...


5

1 - Is there a limit to the number of DHCP Scopes I can deploy to a Windows Server 2012 R2 server? If there is, I'll need to consider adding more DHCP servers now. According to this: http://social.technet.microsoft.com/Forums/windowsserver/en-US/759becd0-9fbe-44e6-aac8-6f50036294c2/windows-2008-r2-x64-dhcp-server-maximum-scope-?forum=winserverNIS There is ...


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