Dynamic Host Configuration Protocol (DHCP)

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18
votes
4answers
13k views

How does a computer obtain an IP address via DHCP?

How does the computer know which device on the network to query? How does the default gateway factor into this? Pretty much, what is the chain of events that occurs when a computer tries to obtain an ...
14
votes
11answers
13k views

Windows 2008 DHCP service fails - “…failed to see a directory server for authorization.”

I have a small environment running Windows 2008 R2 where the DHCP service on the domain controller fails every two weeks. The most-visible error is Event ID 1059 and the Event Viewer message is: ...
13
votes
2answers
2k views

What are the possible issues in using very short DHCP lease time (< 1min)?

We have a network setup for a demo, which lasts about 15mn. Our DHCP server is configured to assign ~ 100 addresses (max number of simultaneous connections or our AP) ... but since people might come ...
13
votes
4answers
2k views

Windows DHCP Server - get notification when a non-AD joined device gets an IP address

SCENARIO To simplify this down to it's easiest example: I have a Windows 2008 R2 standard DC with the DHCP server role. It hands out IPs via various IPv4 scopes, no problem there. WHAT I'D LIKE I ...
11
votes
4answers
1k views

What does a DHCP-client consider to be the “best” answer?

We have training rooms where normally Windows XP is installed (via PXE). The "normal" DNS/DHCP infrastructure are Windows-Servers. The training room has its own VLAN (different from the Windows ...
5
votes
1answer
1k views

Client not getting address from some DHCP server

I'm working on some embedded devices which should be connected to a large network (hundreds of devices) via ethernet and that should be configured using the DHCP protocol. What I'm experiencing is ...
5
votes
1answer
239 views

Is there a way to classify DHCP requests based on the interface they're coming from?

As the question title states, I want to classify my clients based on the interface their requests are coming from. Can this be done with normal matching? Or should I restrict the DHCP server to only ...
5
votes
1answer
654 views

Openwrt isc-dhcpd-4.2.4

Every time the dhcp service starts, it listens not only on 0.0.0.0:67 but also on 0.0.0.0:PORT where PORT is a random number. Anyone knows where this behaviour comes from? root@OpenWrt:/# netstat ...
4
votes
5answers
955 views

Is there an official way to detect an existing DHCP server?

I'm planning a new feature on our product to support a LAN. Since the installation will be done by relatively non-technical people (it's for boats) I was thinking it would be useful to automatically ...
4
votes
4answers
17k views

Force the DHCP server to renew the IP address of a client machine, without doing anything in client machine

I would like to know, if there is a way I could force the DHCP server to renew the IP address of a client machine instantly, without me going to the client machine? In fact, imagine, I don't have ...
4
votes
5answers
1k views

Host DHCP services on server or firewall/router?

I've been debating with myself about the best place for hosting a LAN's DHCP services. I have the option of either on a sonicwall firewall or a Windows 2008 server. The two things I was looking for ...
4
votes
2answers
13k views

Linux DHCP server option 43 vendor-encapsulated-options, how to format/encode?

I admin the network for a small business which has an IPCop firewall box providing DHCP services to the network (and various other services). The DHCP server in IPCop appears to be dhcpd and IPCop ...
4
votes
2answers
170 views

How can i locate rogue DHCP servers? [duplicate]

I am investigating some odd behaviour on a sub-net, where host registration doesn’t list some of the IPs that some users report having. Now that I’ve seen evince, i want to passively scan for the ...
4
votes
1answer
350 views

Running pfSense server after load balancer, dhcp?

I got the following situation: Two wan, load balanced by a hardware load balancing router Wifi network (can be up to twenty AP's) And I need the following: Need a captive portal where clients ...
4
votes
1answer
2k views

Can not authorize DHCP server

I have run into a strange DHCP problem. The thing is the service is running, but the DHCP is not authorized. However, when I try to do it by right clicking, the option to authorize is not there - I ...
4
votes
1answer
370 views

DHCP scope for a user class option

In Linux how can I set a DHCP server configuration which will lease IP addresses from scopes which are defined according to user classes. For example the following configuration leases IP addresses ...
4
votes
1answer
676 views

DHCPREQUEST and DHCPACK spam in logs

I've recently noticed that my android phone (droid dna, although the thunderbolt that I had before did the same exact thing) is rapidly requesting dhcp info my dhcp server (isc-dhcp-server on debian ...
4
votes
3answers
1k views

Cofiguring DHCP server on ubuntu

I am trying to configure DHCP server on Ubuntu but facing some problems. Steps I have followed are given below: Step 1 # apt-get install dhcp3-server I faced following problem during ...
3
votes
3answers
2k views

Stop DHCP client from receiving old IP address on new VLAN

I have one DHCP server running Windows Server 2008 R2. It is configured with one Superscope which contains 5 member scopes. One scope for each one of my subnets. Here is the problem, if I am on VLAN ...
3
votes
4answers
551 views

Can ONE dhcp server serve 2+ network ip range

I have only One dhcp server which has only one interface with ip address 10.0.0.1/24. The dhcpd.conf are like: subnet 10.0.0.0 netmask 255.255.255.0 { <-------working host yyy { ...
3
votes
4answers
383 views

Linux: disallowing access to a network when the user has a static-defined IP address

In my network I run dhcpd3 set up to assign IP addresses only to specific MAC addresses. It works wonderfully, I even integrated it with bind9 to automatically create direct and reverse DNS hostnames ...
3
votes
1answer
3k views

Can a DHCP reservation use an IP address in the exclusion range?

Windows Server 2008 R2, running the DHCP service. DHCP Scope: 192.168.1.1 - 192.168.1.254 Exclusions: 192.168.1.1 - 192.168.1.99 If a reservation uses an IP address in the exclusion range (like ...
3
votes
1answer
4k views

Move DHCP Scopes to existing DHCP Server

We have a remote Domain Controller that is running Server 03'. I'm wanting to retire this box and move to the 03' box that we have locally. I was looking at this guide, but wanted to ensure that it ...
3
votes
1answer
290 views

Multiple DHCP relay servers after one another?

Is it possible to have multiple dhcp relay servers in line? IOW DHCP client <=> DHCP Relay A <=> DHCP Relay B <=> DHCP server
3
votes
2answers
1k views

Using DHCP with Multi-Homed NICs

I am trying to steer away from our current manual addressing system and embrace the decades-old wonder of DHCP. In our domain and even at my home network DHCP is great - I can use address reservations ...
3
votes
4answers
772 views

Resolving IP address conflicts on a LAN

We have our LAN set up with DHCPD providing fixed IP addresses to the systems. However we are facing IP address conflicts if some one connects a laptop and assigns an IP address belonging to another ...
3
votes
3answers
913 views

Ranges for Multiple DHCP Server: Better to overlap or separate? wireless vs ethernet clients?

I know there are mixed feelings about running multiple DHCP servers on one LAN, but I'm wondering about the best way to set their ranges. In my case, I have a router which performs DHCP and also my ...
3
votes
1answer
217 views

Is there a match on incoming interface in DHCPd classes?

(Note, the title of the question Is there a way to classify DHCP requests based on the interface they're coming from? is what I want answered, but it doesn't actually ask that question for a ...
3
votes
1answer
1k views

Getting same IP address for cloned Virtual Images

I was trying to install 3 VM and instead of creating them individually (by using the New VM) I actually cloned them. Now after I start the VM (they are running in the bridge mode) all the VM's are ...
3
votes
2answers
657 views

Assign fixed IP address via DHCP by DNS lookup

Preface I'm building a virtualization environment with Ubuntu 14.04 and LXC. I don't want to write my own template since the upgrade from 12.04 to 14.04 has shown that backwards compatibility is not ...
3
votes
2answers
1k views

Setup DHCP split scope but second server won't give leases

My work setup had only one Windows 2003 DHCP Server which resides on DC01. I wanted to improve the redundancy for DHCP so I installed DHCP services on another server (DC02) which is also a DC and DNS ...
3
votes
1answer
128 views

ISC DHCPD memory leak solutions and or workarounds

Background: I have recently been put in charge of finding the root of and/or fixing a memory leak with an ISC DHCPD (4.2.5-P1) installation on a Debian (Lenny) Unix server. I have been researching ...
3
votes
2answers
251 views

Prefix Delegation and route creation

I'm using the ISC dhcp server version 4.1 for DHCPv6 prefix delegation on a network. When the server allocates a prefix to a client, the server does not create a route for that prefix to the client ...
3
votes
2answers
1k views

Secondary DHCP server won't start on Centos 6.2

I'm trying to create a backup DHCP server. Server times are in sync. Primary server starts fine. Secondary server won't start. Error from /var/log/messages is: Sep 15 14:47:45 stream dhcpd: ...
3
votes
1answer
6k views

Windows 7 Failing Ping on IPv6 in DHCP Setup

I have set up a test ISC DHCP server that is not connected to an internet with DHCP and DHCPv6. I also have a Cisco 3750G with IPv6 enabled. I have firewalls off on both machines. My Windows 7 ...
3
votes
0answers
947 views

DHCP Server Not Offering to PXE Client

DHCP Server Not Offering to PXE Client BACKGROUND: I'm in the process of adding PXE services to an existing SCCM 2007 server. The SCCM server is separate from the DHCP server (Server 2008 x86) and ...
2
votes
4answers
1k views

Is a short DHCP lease from my ISP likely to cause problems?

I'm wondering if having a short DHCP lease is likely to cause any issues, such as: Dropped VoIP calls Dropped VPN connections If so, could you explain why?
2
votes
2answers
321 views

Multiple DHCP servers available to virtual networks in VMware - how to set priority?

In a VMware ESXi 4.1 lab environment*, I have a pair of virtual networks configured (10.0.4.x and 10.0.10.x). On both networks is a DHCP server. The problem is that the networks are routable to each ...
2
votes
4answers
7k views

Configuring DHCP on RHEL 6

I have a fresh install of RHEL6 and I am unable to find any config file to do advanced configuration for dhclient. I am trying to find something like dhclient.conf on Ubuntu so I can modify options ...
2
votes
2answers
2k views

Unathorizing and removing DHCP role

I am removing DHCP from one of my server (Windows Server 2008 R2 Enterprise), besides running: netsh dhcp delete server server name *server IP* and the removing DCHP role itself from Server ...
2
votes
2answers
120 views

Technically, could I use DHCP on a DHCP Server?

I know that it is not usual, but could I use dinamic IP address on a server that is running a DHCP Server instead of setting a static IP address on it? Is there a restriction of my Windows DHCP ...
2
votes
3answers
4k views

Multiple PXE server same subnet

I've been struggling with this for some time. I have a few test machines that boot from the network, they receive the boot data from the DHCP server, this tells them who is the boot server where is ...
2
votes
1answer
94 views

set unlimited lease duration throuth CMD

On Windows Server 2008 (R2, 32-Bit, I found the following way to set the lease duration for, say, 3600 Seconds (1 Hour). netsh dhcp server scope 10.0.0.0 set optionvalue 51 DWORD 3600 [→ source] ...
2
votes
2answers
300 views

windows server 2008 DHCP ran out of IP addresses

I have a Windows 2008 server with 1 DHCP Scope 10.0.0.X/255.255.255.0 and watchguard firebox for my internet router. I have run out of IP addresses. I added a second scope to my DHCP server, and I ...
2
votes
1answer
499 views

IPV6 Bind/DNS DHCP

We are run the one event in that there 7000 people are visiting, with Laptop to provide then internet access. We thought of setting up IPV6 DNS/DHCP all this people will be use LAN cable to get ...
2
votes
3answers
973 views

How to forward DHCP requests through router to Win 2k8R2 server?

I have a D-Link DGL-4500 and I've been using that for a long time as my DHCP server. I now have a Windows Server 2008 R2 machine plugged into it and I have set it up as a DHCP server. I don't have 2 ...
2
votes
1answer
45 views

Are MAC ID passed via DHCP Relay

Do MAC ID pass through dhcp relay? Even if its connected on the WAN from the internet? So if the DHCP Server is on the WAN of the router and connected to a DHCP server on the internet is it passed?
2
votes
1answer
301 views

DHCP Warning Sign Icon On Windows Server

I have a Windows Server 2008 R2 SP1 Domain Controller. I have the roles AD, DHCP, and DNS installed on this server. I noticed today that there was a warning sign on my IPv4 setting, but not on my IPv6 ...
2
votes
2answers
381 views

Static lease IP dhcp within dynamic range pool

I am using fedora 13. I want to statically bind a MAC to IP. Now the problem is if the IP is within the range pool, it may get allocated to some other host also. For that I use a tweak, where I ...
2
votes
2answers
138 views

DHCP/static IP nomenclature

I've just inherited systems administration for a small network, on which we have exclusive access to the first 128 IPs on a private virtual subnet. We have a DHCP server which binds IP addresses to ...