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52 votes

Rogue DHCP Server Can't be found

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 ...
joeqwerty's user avatar
  • 111k
38 votes

Rogue DHCP Server Can't be found

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 ...
Dave Stuart's user avatar
18 votes

Rogue DHCP Server Can't be found

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 ...
Adam Davis's user avatar
  • 5,446
17 votes

Rogue DHCP Server Can't be found

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'...
Aaron Tate's user avatar
  • 1,222
12 votes
Accepted

Can the network still work when DNS & DHCP go offline?

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 ...
kasperd's user avatar
  • 30.7k
7 votes
Accepted

VCenter has failed, DHCP server is down

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 ...
joeqwerty's user avatar
  • 111k
6 votes
Accepted

IPv6 address lifetime: preferred versus valid lease

The best explanation I have seen is in the introduction to RFC 4862 (which you should read in its entirety later): IPv6 addresses are leased to an interface for a fixed (possibly infinite) length of ...
Michael Hampton's user avatar
5 votes
Accepted

dhcp server gives "no free leases" error although there should be available IPs

It looks like you miss either range definition or a specific host entry for those boxes, matching their MACs. Unless your failing boxes are on the list that "goes on like this", they won't have any ...
Grigory Sergeev's user avatar
5 votes

Unusual DHCP activity after power outage

It is not an answer to your question as I feel there is not enough information to really determine what happened. To prevent issues with DHCP servers many system administrators prefer to give their ...
Tommiie's user avatar
  • 5,675
4 votes
Accepted

how dhcpd handles static IPs vs DHCP reservations

Static IPs are normally outside the pool range as you do not want static IPs assigned to other hosts. As long as the static IPs are in an IP range local (or relayed) to the DCHP server they can be ...
BillThor's user avatar
  • 28k
4 votes
Accepted

How to configure a MikroTik hAP ac lite router as a Layer 2 switch?

Just bridge every interface on hAP and it will act essentially as a switch. That's it pretty much. Then remove or disable any dhcp-server instances on IP > DHCP-Server. Since you do not provide any ...
Cha0s's user avatar
  • 2,460
4 votes
Accepted

dnsmasq not responding DHCP requests that don't follow a DHCP discover

The answer is to use --dhcp-authoritative option in dnsmasq. The problem was that I was restarting the dnsmasq server each time, so it had no lease file, but dhclient had its own lease file. Not being ...
Ricky Robinson's user avatar
4 votes
Accepted

DHCP renewal can't go through because DHCP server is down

Renewal usually happens before expiration - most often starting at 50% lease time. If the lease eventually expires before a renewal can be DHCPACKed, the client must not continue to use the leased ...
Zac67's user avatar
  • 11.9k
3 votes
Accepted

How to disable NetBIOS over TCP/IP on pfSense via DHCP

Add an additional option of 43 / String / 01:04:00:00:00:02
Corey's user avatar
  • 2,081
3 votes

can a windows server 2012 act as a domain controller to only a select range of ip addresses?

The DHCP server can service both domain members and non-domain members. You don't need to do anything special to have it service non-domain members. Simply join the domain from the machines you wish ...
joeqwerty's user avatar
  • 111k
3 votes
Accepted

How to list DHCP options sent to a client from a DHCP server in Windows?

The best way to would be to use something like WireShark to view DHCP packets. However, the DHCP options are stored in the registry, look in the key Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\...
Bert's user avatar
  • 3,043
3 votes

dhcpd class match on hostname or mac address

For the first question: does an "allow member" statement implicitly deny everything else ? Well the question is answered in the manpage of dhcpd.conf: If a pool has a permit list, then only those ...
silmaril's user avatar
  • 511
3 votes

dhcp server gives "no free leases" error although there should be available IPs

Your ISC dhcpd config file (posted June 2016) has no range statement. No leases are free because the server can't find an IP address, in a defined range, to hand out. You need a line like range 10....
user3213669's user avatar
3 votes

how dhcpd handles static IPs vs DHCP reservations

Some DHCP server software operate differently when it comes to reservations: some require that all reserved addresses be outside the dynamic range but be within the subnet. some require that all ...
BeowulfNode42's user avatar
3 votes
Accepted

An active directory domain could not be contacted

OK, the problem is that the client has an APIPA address (169.254.139.214), which means that it isn't getting an ip address from DHCP. I can see in your screenshots that the DHCP server has a red arrow,...
joeqwerty's user avatar
  • 111k
3 votes

How to ignore unused network interfaces in dhcpd on Centos 7

You don't need to add the interface line if it is on a different subnet. The Slackware 14.2 Linux distribution provides the following example: # No service will be given on this subnet, but declaring ...
Parker's user avatar
  • 783
3 votes

Does a Windows host correctly interpret dnsmasq parameters?

I found the problem: my DNS settings on the client were static. The IP was assigned via DHCP. This is not normal and what brought me to check that is that I have had the same issue of the DNS ...
WoJ's user avatar
  • 3,667
3 votes
Accepted

Windows Server 2012 Failover DHCP

Scope options and reservations are not replicated automatically. See this comment from "Microsoft Windows DNS, DHCP and IPAM Team Blog". There is a Powershell Cmdlet in Server 2012R2: Invoke–...
duenni's user avatar
  • 2,959
3 votes
Accepted

Microsoft DHCP only for reserved addresses

In the DHCP console: Enable the Allowed List filter: Right-click on IPv4 and go to Properties Click the Filtering tab Check the box next to Enable Allow List Make sure the box next to Enable Deny ...
pat o.'s user avatar
  • 1,989
3 votes

split dhcp subnet in two parts

Your configuration should look more like this: subnet 1.2.3.0 netmask 255.255.255.0 { range 1.2.3.128 1.2.3.254 next-server 1.2.3.199; filename "pxelinux.0"; option routers 1.2.3.1; option ...
longneck's user avatar
  • 23.2k
3 votes
Accepted

Server 2012R2 DHCP & DNS Updates

The ability to register both A and PTR resource records enables a DHCP server to act as a proxy for clients running other operating systems. DHCP requires the use of DNS dynamic update to keep name-...
Net Runner's user avatar
  • 6,249
3 votes
Accepted

Deploying DHCP Role and Configure it in too many sites

Are you running 2008 or 2008 R2? if you are running 2008R2 then Microsofts Desired State configuration (DSC) can be used to deploy and configure DHCP. It can be used to target multiple servers, think ...
Michael Brown's user avatar
3 votes
Accepted

Windows 2008: DHCP server with "holes"

One way you can do this is increase your existing DHCP scope to the entire 192.168.0.0/23 network and then create exceptions for the blocks of addresses you want to use as static IP addresses.
user5870571's user avatar
  • 3,164
3 votes
Accepted

install DHCP on Windows Server 2016, but not start the Service

You can safely install the DHCP role. It isn't functional until you authorize it, configure a Scope, and activate the Scope.
joeqwerty's user avatar
  • 111k
3 votes
Accepted

Why is this checkbox disabled in Windows DHCP server range policy / vendor class management?

It looks like you are managing a Windows Server 2012 DHCP server remotely from a Windows Server 2012 R2 server. Prepend wildcard was introduced in Windows Server 2012 R2 and is not available in Server ...
Mike M's user avatar
  • 1,142

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