DHCP stands for Dynamic Host Configuration Protocol and is an auto configuration protocol used on IP networks and an extension of the Bootstrap Protocol.

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DHCPD Offering ip address on wrong subnet

I just recently added a new subnet for our wireless network to our DHCP configuration for the 192.168.254.0 subnet. Most of the time when wireless clients connect it works just fine. However, ...
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302 views

ISC-DHCPD failover, Modifying host definitions via OMAPI

Background: I'm working on replacing my single DHCP server with 2 in a failover configuration. When I do a DHCP request I see the lease is created in both dhcpd.leases files on each server. However, I ...
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219 views

Can multiple VLANs be provided with multicast addresses by a single MADCAP server?

Can a single DHCP server provide dynamic multicast addresses for hosts in many VLANs using MADCAP, just like it can provide hosts with unicast addresses via ip-helper? Or from a Cisco perspective, ...
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325 views

Logging dhcrelay, other than redirecting the -d debug option?

I am hoping to find a way to log the activity of the isc dhcrelay service, apart from redirecting it's "-d" debugging output to a file and logrotating it. I need a long-term record of what the ...
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149 views

Multiple NICs config, disconnecting eth0 disconnects all other interfaces

Good Day, I'm using hardware that streams data, it has 4 Lan ports and is running Linux 2.6.23. I've run into some strange behavior with ARP tables reporting multiple IP addresses to single MAC ...
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148 views

Wireless router not allocating correct IP addresses

I have a WAG320N wireless router setup as a DHCP relay to my Windows 2003 R2 Enterprise server. The IP of the router is 137.248.21.1 The IP of the server is 137.248.21.10 The scope for the server is ...
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493 views

How can you route DHCP requests through a non-default gateway?

I'm hosting some KVM virtual machines on a server with two NICs, eth0 and eth1. I have two networks 192.168.100/24 and 192.168.200/24. I have set up bridges as per ...
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276 views

Windows Server 2008 DHCP with RRAS

I have a Windows Server 2008 R2 which is a member of a domain, but is placed in a remote location. The server is directly connected to Internet. Clients need to access a particular insecure TCP ...
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305 views

associate dhcp requests with subdomains in dnsmasq

I have dnsmasq running as a dns server with a number of linux boxes using static ips that run several virtual hosts on subdomains. I currently have the following address line in my dnsmasq.conf to ...
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17 views

cisco ip helpder-address not working

I have 3 Cisco Catalyst switches: 2 3750 series and one 3550. The appear to suffer from the same problem. If I define a VLAN, configure a DHCP address assignment on it and then issue a command for it ...
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19 views

How to configure DHCPv6 and DNSv6 configuration in Ubuntu 12.04?

I'm planning to configure DHCPv6 and DNS server in my network. I would like to understand whether both DHCPv4 and DHCPv6 can be configured using isc-dhcp-server service? When i tried nslookup ...
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4 views

How to set up a simple Cisco ISG config for controlling internet access

First off, here is my config so far. http://pastebin.com/fV2NGCE2 I've gone through a few guides online and the 15.2s manual and the xe3 manual for Cisco's ISG (intelligent services gateway) and ...
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26 views

DHCP Server ignores DHCPDISCOVER request

Within a VPN I am trying to implement dhcp. I have the following setup now: DHCP Server (dnsmasq) is listening/should listen on a virtual network interface. The interface is configured as follows: $ ...
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15 views

WES09 Client not registering with dns suffix

I have HP thin clients, some running Windows Embedded Standard 2009, and some running WES 7. They are all getting DHCP addresses from our Server 2012 R2 DHCP server, with AD integrated DNS. With both ...
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19 views

DHCP export using netsh

I'm trying to export a DHCP database using the following command: netsh dhcp server export c:\dhcpdb.dat all However it completes with the error WARNING: Could not obtain host information from ...
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35 views

Setting DHCP hostname with Cobbler

I have configured the DHCP to work with Cobbler in a way that the client will get its hostname assigned by DHCP (by using the option host-name in /etc/cobbler/dhcp.template). It works fine if I run ...
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9 views

Ubuntu DHCP-RELAY Error

I have a Ubuntu 14.04 server running as a router (4 NICs with IP forwarding turned on). The routing/forwarding component is working fine. However, I now wish to implement a DHCP-Relay/IP helper so I ...
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26 views

Use export-smigserversetting vs. export-dhcp

Any reason to use one over the other (export-smigserversetting vs export-dhcp) when migrating DHCP from Server 2008 to server 2012 R2?
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16 views

Hyper-V with DHCP enabled Host

I am trying to set up a Hyper-V enviroment. This is what I am trying to do : Install Server 2012 r2 on the machine as the HOST. Install DHCP, DNS and Hyper-V on the Host Machine. Using Hyper-V ...
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22 views

Unique record per ip address on Windows DNS

I have a little problem with my DNS server under Windows domain. My DNS server gets automatic registration from clients by dhcp. Please consider this situation: Computer PC01 with dhcp address ...
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39 views

Create IPv4 reservation with DUID in Windows Server 2012 DHCP

Can I configure reservations for IPv4 addresses in Windows Server 2012 DHCP for systems which send DHCP requests with a DUID for their client identifier (Option 61)? I have Linux (e.g., Fedora 21) ...
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23 views

IPv6 DHCP for Hyper-V Guests

I have the following configuration: W2K12 with Hyper-V and DHCP Role installed, and I have IPv6 block. The goal is to assign IPv6 via DHCP to guest VMs, and make guest VM to have access to the ...
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11 views

How can I assign an IP by UID in DHCPd

Here was answered how to assign an IP by MAC address. I want DHCPd server to assign IP by UID. Can i just add record to dhcpd.conf in the same manner? For example: host example { uid ...
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10 views

Group reservations in Windows Server 2k12 R2 DHCP

I am moving a mixed network from a Linux DHCP server to a Windows 2012 DHCP. Because of some of the applications our Linux users need, we need to specify different DNS servers for Linux and Windows ...
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36 views

DHCP from Cisco 1921 failing after switch nr 2

I have a network which uses a Cisco 1921 router. The router is connected to a Dell Powerconnect 2848 switch and from that switch is a connection to a small SOHO Planet switch which 3 computers connect ...
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41 views

DHCP relay offer packet dropped

I'm trying to get DHCP relay set up on our Cisco SGE2010P switch. Sadly, we can't afford a catalyst switch right now. It looks like I have everything configured correctly, but something is going ...
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62 views

OpenVZ, veth interface and getting ip from dhcp from the inside of containers

I have OpenVZ server (centos) with one interface eth0, also I have dhcp server in the same network. I need container with ip from dhcp server. So, I created guest node with the veth interface, after ...
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33 views

Windows Server 2008 reboots when DHCP server is down

I have two Windows Server 2008 servers. Both of them have static ips, both of them are domain controllers. The first one run a server based software, the second one is our dhcp server. Some times the ...
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17 views

pfsense router dhcp “periodic error: no ip”

A simple /20 subnet with aprox 300 users. All DHCP. One LAN only Sometimes some of the users report that they get no IP. After minutter or as long as an hour they regain access. Unfortunately ...
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64 views

Windows DHCP client only using one DNS server?

I have a PC running Windows 7 professional. It is a DHCP client. The DHCP server is sending it two DNS servers. This has been verified with packet captures. However, after running ipconfig /release ...
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33 views

Small Office WiFi config for iPhones

I purchased an ASUS RT-AC66u wireless router for use in a small office. I have the router configured as an access point, DHCP is turned off. It is using a static IP of 10.10.10.251. My DHCP server ...
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34 views

DirectAccess Multiple Subnet Deployment

I am looking at doing a DirectAccess rollout on AWS using a single Server 2012 R2 instance behind an edge device. My clients are mostly running Windows 7 Pro/Ultimate, but there will be some other ...
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68 views

DHCP Requests cannot get through Switch

First a little about the network setup: We are a smaller department of a larger school. We have 7 offices with TP-Link managed switches as well as 20 APs and 24 classrooms. The switches, APs and ...
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45 views

DHCP Server configuring

I've been configured DNS and DHCP on Windows Server 2012 correctly. But when I open the DHCP server from start menu and server manager, I get different result. When I run DHCP manager from server ...
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119 views

Internet drops out randomly for short periods of time (LAN issue)

I run a network (I'm just a math teacher) at my school. We get random 10 or so minute periods (I'd guess three a day on average) where the Internet is not accessible from within the LAN. If I go to ...
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173 views

Why need DHCP Relay (Watchguard) inside the Trusted network?

I run a small network that looks like this: { Win 2008 server , desktops , Wifi AP} -> Switch -> Watchguard XTM21 firewall (the Switch is connected to the XTM's Trusted interface ; the XTM ...
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21 views

Change network mask DHCP server

Currently i have a Ubuntu with isc-dhcp-server running with the following configuration authoritative; ddns-update-style interim; ignore client-updates; subnet 192.168.1.0 netmask 255.255.255.0 { ...
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151 views

Sonicwall L2TP Server is using a “phantom” internal DHCP server

Following a few articles on options 121 and 249, I'd like to push out routes to the L2TP VPN clients using the internal DHCP server on the Sonicwall. However, the Sonicwall seems to be using a ...
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37 views

How to identify hosts with bridged adapters

We have an issue with our Windows DHCP server randomly having bad address errors. The current top theory is that there is a host within that pool with bridged network adapters, causing all sorts of ...
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29 views

What is the default behavior when a RHEL 6.x DHCP client fails to renew its address?

I have had experience with some RHEL 6 servers that were found unreachable, and investigation of the console revealed that they had failed to renew their IP address, and eth0 was without an IP. There ...
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80 views

DNS options on Cisco switch providing DHCP

At the company work for we decided to move DHCP duties from a Windows server to our 3750-X switch stack that's the gateway for our network. I researched the commands needed and cobbled together the ...
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40 views

Draytek AP Wireless Bridge IP Issues For LAN Devices

OK, I have a very messy network at my office, piggybacking off a neighbor's WIFI for internet (with their permission). I have a Netgear Router + DNS (DGN2200) connecting via LAN to a Draytek 800AP. ...
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52 views

How to fix stalled connection on large download

I have a cisco 1921 router performing routing and NAT function. Cisco 3750 is performing layer 3 core switching duties. Users are complaining about large file transfers being stalled (not dropped) ...
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60 views

WDS and DHCP - PXE-E11/55 errors

I have been doing some testing with MDT/WDS and yesterday, out-of-blue, my virtual PC doesn't want to boot from a network to WDS server. Here is the setup (all stations are virutulized, vSphere 5.5): ...
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122 views

ISC DHCP Server - Client Uplink Is Not Working

Running a DHCP server, client(s) does not have up-link (0Mbps) and has a downlink (50Mbps.) I am setting up a gateway/router on a PC running Debian Wheezy with ISC-DHCP. I have 1 WAN (eth0) and 2 LAN ...
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273 views

OpenVPN Linux Client does not bring up tap0 interface

I have an OpenVPN client on Linux connecting to an OpenVPN server. The server assigns IPs via DHCP, thus I connect using the tap interface rather than the tun interface. OpenVPN connects, ...
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232 views

Issuing 'ip dhcp relay information trusted' command on a VLAN interface

I was reading this article - Allowing option 82 in Cisco DHCP relay agents. It says As a security measure, Cisco IOS will not forward DHCP requests that contain Option 82 information and a ...
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365 views

Windows 7 Pro - DNS Servers changed on DHCP-enabled workstations over weekend, not sure how

This morning I came in to our SOHO office (>5 users) to reports of the internet not working. I tried all the usual simple fixes like cycling switches (each user has a switch at their desk) then I ...
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69 views

DHCP User Class ID Notation (numerical vs. ASCII)

Creating a new DHCP User Class (on Windows Server 2008 (R1) 32-Bit) on can set a "Display Name" – here SuperDuperClass – and define the User Class ID numerically (1st & 2nd column) or ...
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3k views

Samba4 Internal DNS with DHCP Server

On FreeBSD we run Samba4 as a DC and until recently had our IP addresses handed out by the routers DHCP server. We switched to running a DHCP server on the FreeBSD machine with the following ...