DHCP

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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Hi,
My client has a few rooms which have network ports connected back to the router.
I can plug my laptop in the network ports in the rooms and access the internet without a problem.
But when I configure a wireless access point on that same network port and try to access the new SSID, I get no internet.
The AP doesn't pick up internet or an IP address from the router.
I've tried 5 different access points.

I've done this in the past few years about 20 times and it always works. Configuring an AP is very simple.
So I'm confused why these AP's do not pickup IP's from the router but a laptop connected to the same cable can pickup an IP.
0
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My church has a C2851 that has 3 vlans.  It provides DHCP to 2 of those.  The other dhcp is provided by a windows server.  The server vlan never loses connection to the internet but the other 2 access the internet for a day or two then stop until I reboot the router. Below is the interface setup & dhcp pool.  Am I doing something wrong?

ip dhcp pool guests
   network 10.10.0.0 255.255.252.0
   default-router 10.10.0.1
   dns-server 8.8.8.8
   lease 0 12
!
ip dhcp pool Employees
   network 172.28.0.0 255.255.252.0
   default-router 172.28.0.1
   dns-server 8.8.8.8
   lease 0 12
!
!





interface GigabitEthernet0/1.100
 description Admin vlan 100
 encapsulation dot1Q 100
 ip address 192.168.1.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly in
!
interface GigabitEthernet0/1.110
 description Employees vlan 110
 encapsulation dot1Q 110
 ip address 172.28.0.1 255.255.252.0
 ip nat inside
 ip virtual-reassembly in
!
interface GigabitEthernet0/1.200
 description Guest vlan 200
 encapsulation dot1Q 200
 ip address 10.10.0.1 255.255.252.0
 ip nat inside
 ip virtual-reassembly in
0
Hello
Im trying to configure ISC DHCP to work with Microsoft DNS. The following dhcpd.conf file creates the Forward Lookup Zone entry but it doesnt create the Reverse Lookup Zone entry.  Im pretty sure it is possible but Im stuck.  The entry is I believe being created via the device, not by the dhcp server.  I checked the dns entry and it has the hostname$ with modify perms.

Any help is appreciated.  Thanks!

dhcpd.conf - primary
#authoritative;
ddns-updates on;
ddns-update-style interim;
ddns-domainname "example.com.";
ddns-rev-domainname "in-addr.arpa.";
allow client-updates;
one-lease-per-client true;
omapi-port 7911;

#Failover specific configurations
failover peer "dhcp-partner" {
  primary;
  address server1.paychex.com;
  port 647;
  peer address server2.paychex.com;
  peer port 647;
  max-response-delay 60;
  max-unacked-updates 10;
  mclt 3600;
  split 255;
  load balance max seconds 3;
}

include "/etc/dhcp/master.conf";

Open in new window


dhcpd.conf - secondary
#authoritative;
ddns-updates on;
ddns-update-style interim;
ddns-domainname "example.com.";
ddns-rev-domainname "in-addr.arpa.";
allow client-updates;
one-lease-per-client true;
omapi-port 7911;

#Failover specific configurations
failover peer "dhcp-partner" {
  secondary;
  address server2.paychex.com;
  port 647;
  peer address server1.paychex.com;
  peer port 647;
  max-response-delay 60;
  max-unacked-updates 10;
  load balance max seconds 3;
}

include "/etc/dhcp/master.conf";

Open in new window


master.conf

Open in new window

0
Hi all,

Hope there are some die-hard APC fanatics on this forum :-)

Baught a second hand APC SMT1500I with AP9619 NMC1 network card in it for a very nice price.
Hooked it up and found out quickly that it has an assigned IP adress  (green solid network led).
Tried to set up a connection with hyperterminal and TeraTerm as well in order to reset the IP-settings and password of the previous owner.
Built a RJ45 to DB9 serial cable (http://pinoutguide.com/UPS/apc_0625_cable_pinout.shtml) and bought an USB to RS232 converter.
Hyperterminal tells me there is a connection between my pc (even without being connected to the AP9619) but I get no login prompt, even after many enters and the reset button on the network card (green/orange flashing). So I setup and old XP pc with Tera Term with the same results.

I tried many settings (2400baud 8n1 no flow in each setting, changed pin number 2 and 3 for nullmodem configuration and all the possible varieties. I also connected the PC directly to the network card, changed the network card into static in the same 10.100.0.xxx range (thanks to wireshark network sniffing software that pointed out the adress 10.100.0.55) browsed to this adress and got a message, there had to be logged in via a ssl connection. (of course this didn't worled out well.....). Half a day later I am really stuck...

Does APC needs qualified rocket scientists in order to achieve a simple network card?

Hope that there is a whizkid between all the …
0
I would like to separate hard wired connections from wifi APs.  The purpose is to separate traffic and assign separate class c subnet to each group.  

Equipment used
Watchguard firebox
Qty 2 Uniquiti 24-port Poe+ 500 watts
Qty 10 Uniquiti HD access points.

Separate subnets for each group:

Hardwire users
10.1.1.1/24 on port 1 of Firebox with dchp turned in - hardwired - connects to first Uniquiti switch.  

Wifi access points
10.1.1.2/24 on port 2 of Firebox with dhcp turned on -  WiFi access points - connects to Second switch.

Problem
The second Uniquiti switch that connects the hardware connections  - port 1 disconnects or the ubiquity access points will start missing heart best and disconnect

 Firewall policy set to  any traffic can pass between the the Firebox interface ports 1 and 2.  Ping traffic passes from and to sinners with issue.

If all the devices / hard wire and access points and the two switches - are put into 1 single subnet - no issues.  

Comments would be appreciated.
0
In Windows there is a checkbox "Register this connection's addresses in DNS".  See attached screenshot.
What is the equivalent in
- Ubuntu Workstation
- Raspian (Raspberry Pi Debian variant)

Thank you
0
I will soon be migrating our AD domain controllers to Server 2016. We have a few DC's in the 1 forest but the one that holds the FSMO also has a lot of other services like DHCP and its a certification authority. I've come up with a very high level list of the process involved, id like to see if I am on the right track by the experts on here. My main concerns are over keeping the same IP and Name as the old DC and moving the certification authority.

The server I'm looking to migrate initially is ADC1

1.      Move services to ADC2
   a.          Move RD Licensing Server
   b.          Move DHCP (or test if we can use the failover DHCP (ADC3) server)
   c.          Migrate FSMO roles
2.      Backup Certification authority on ADC1
3.      Find out what KMS keys are used on ADC1
4.      Remove Certification authority services from ADC1
5.      Turn off ADC1 and test connectivity and logons.
6.      Turn ADC1 back on.
7.      Demote ADC1
8.      Remove all entries for ADC1 from DNS and AD schema
9.      Create new 2016 server (with same IP and name as removed DC) and promote to DC
10.      Upgrade forest schema to 2016
11.      Install certification authority on new DC and restore from backup
12.      Reinstall KMS and keys on new server
13.      Move DHCP back to ADC1 and ensure failover is still working to ADC3
14.      TEST DNS and AD replication.
0
Hi all,

Hope you doing good,

I enable the dhcp relay in checkpoint firewall, user are connecting to SSID but not getting the ip address from the DHCP server.
0
Im looking for some help or recommendation on how I can monitor ISC DHCP more closely.  

  • Id like to know when a scope is close to being fully utilized -- 85-90%?
  Threshold of scope - run out of IPs
   /var/lib/dhcpd/dhcpd.leases
  • dhcp.service stops
  • dhcp failover occurred.


report a WARNING when the Secondary DHCP server kicks in (starts serving addresses due to an issue with the Primary)
report a CRITICAL when both the Primary and Secondary aren't active

Monitoring the dhcpd process running/stopped is unfortunately not really a good solution

Thanks!
0
Every two days after DHCP server not releasing any IP address, I have to restart DHCP server in order to get IP addresses for all client devices. Need any of your expertise . HELP
0
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Greetings !
     I have a hybrid environment with vmachines running locally and on the web (Rackspace).  With my current configuration I have a VPN tunnel between both environments.  The problem is when I lose power, my internal servers and peripherals crash and when they are brought back up it is hard to get DHCP services back online, bring up the tunnel,  etc.   Is it possible to set it up where my internal servers fail over to another DHCP server I could set up at Rackspace?  The advantage being that once power is restored they could instantly get leases, etc.  Is this something covered in the 2012 MS server DHCP functionality?  Ultimately I would like to set something up which "takes care of itself".

Thanks,

Eric
0
Hi,

I have interview at microsoft GTSC. can some one please share me case scenario and troubleshooting questions on below topics.

I know the basics, just looking for troubleshooting scenario based questions on the below topics. thank you.

1)  FSMO Role
2)  Active directory site, service and replications.
3)  DNS
4)  DHCP
5)  Group policies
6)  Replications issues, log analysis,
7)  migration Ad
8)  authentication policies like  kerbros, LDAP
0
Customer has an Arris DG3270 (cablemodem/4-port router) with a switch connected to one of the 4 LAN ports on the Arris router.  Symptom is occasional (random, a few times per day) the devices connected through the switch lose connectivity (yellow triangle shows).  Devices are CC terminal, Win7 POS term, Mac, Win7 PC.  Devices connected directly to the router retain connectivity.  We can restore connection to switch devices by unplugging the Cat5e cable between the router and switch and reconnecting it.  We've tried changing the switch (Netgear, DLink, TPLink), but the symptom persists, so it seems likely the problem originates with a device connected to the switch.  I've run RogueChecker to see if there's more than one DHCP source, run IP Scanner to see what it finds on the LAN.  Nothing looks out of the ordinary.  Any suggestions on what else we can try or check?
0
Hi everyone, my question is same as relevant subjected issues mentioned above, my server 1 have running dhcp and 2 server have seperate wds installed, when i go through to boot from pxe there are tftp open time out and show pxe E32 error. Even port 66 and 67 are checked mark in server options in dhcp server.
somebody give me best possible solution to get out of this situation.
0
I have configured router as dhcp server with pool 10.1.1.0/24 and routing is off. when machine gets dynamic IP via dhcp suppose 10.1.1.1, it is stored in dhcp binding table right?.After that my machine released that IP ,and I cleared dhcp binding and asked for dynamic IP again from dhcp server,this time it provided me 10.1.1.2.why not 10.1.1.1? I repeated that process again after getting 10.1.1.2 and this time it has given 10.1.1.3 .
0
Dear Sir we have wifi routers in our internal network that are connected thru lan switches. wifi routers connect with wire in WAN port and then further Routers DHCP change the class for routers client, i am able to control the traffic of WAN port IP from TMG but unable create a different rules for routers clients.....
any idea please..!
0
I setup wifi in a 4 bed 2 storey house & there have been alot of wifi issues!
Multiple devices & 4 heavy users.
Apple Tvs, Ipads, Macbook, Iphones & 2 windows laptops
Constant drops on wifi & constant reboots of Fiber router.
EG Freezes when watching netflix & need to connect to another SSID.
They get approx 50mb download from the router (which also has wireless enabled)
They didn’t want to wire so i used 4 tplink powerline av600’s
(i’ve used them before with little issues)

http://uk.tp-link.com/products/details/TL-WPA4226-KIT-V1.2.html

So i’m thinking of just swapping out the AV600’s with Archer C2 wifi routers & using standard tplink powerline plugs

http://www.tp-link.com/us/products/details/cat-5506_Archer-C2.html

I setup as Access Points.
I disable dhcp, wan, use separate channels, disable firewall,nat,guest network. I set dns to 8.8.8.8 & 8.8.4.4
All have seperate SSID's. A mix of 2.4 & 5G.
I set the 2.4 channel width to 20mhz
I’ve been testing on my home network & it works fine then just loses connection for a couple of mins.
Happens every hour or so.
I get obscure DHCP error messages in the system log.
I upgraded the firmware & it’s more stable but not perfect.
I try continuous pings from a pc & ipad & they seem fine?

Other than hard wiring is there any advise to minimise issues?
Or is it a limitation of powerline?
0
hello

what is dhcp relay agent and bootp ?
0
Hello I have been asked to set a new Active Directory Site from scratch to mirror a Domain with at least 8 other sub domains no migration will be taking place just the existing naming conventions taken and then set up the platform that I will be using is 2012 OS, I will be setting up a new DHCP, DNS, Cert server.etc. I would apprechieate any advice on how to start achieving this and any really good tools for making the transistion nice and easy.
0
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# systemctl start dhcpd
Job for dhcpd.service failed because the control process exited with error code. Se e "systemctl status dhcpd.service" and "journalctl -xe" for details.
0
Currently have interfaces set up with (2) vlans

mgmt 86
cpe 87

When controller is set to tunnel traffic and use controller as gw - clients are able to get an ip off ruckus ap.
When controller is set for nomadix to be gw - clients are NOT able to get an ip off of ruckus ap.

As it stands, I'm trying to understand what is preventing clients from using nomadix as gw.
Cisco box is currently set to switch mode with the following for int:

 interface gigabitethernet1
 switchport mode general
 switchport general allowed vlan add 87 tagged
 switchport default-vlan tagged
!
interface gigabitethernet2
 switchport mode general
 switchport general allowed vlan add 87 tagged

Please keep in mind that I am testing a ruckus ap on int2 and can access internet if traffic is tunneled to ruckus controller. What's odd to me is that the cpe vlan for the ruckus controller is not even on this cisco switch but I'm able to pull a cpe ip.
 
To reiterate, I am having trouble getting an ip when controller is set to using the nomadix as a gw for client ips.

Looking for any enlightenment as I've been working on this for a few days already and am stumped.

Thank you!
0
we have a network that has load balancing on a pfsense 8860 router.

We want to add wireless for the guests, and a second SSID for anyone who needs to access the internal network, we were thinking on a separate internet connection for the access points, I am including a diagram of our thought ( at least that is the thought at the moment)NETWORK.pngwe are going to use Aruba IAP225 access points.
We will create two SSID's one for accessing the internal network and one that is a Virtual Guest SSID which the Aruba AP will control the DHCP of.

We want to make sure that the internal networks data is protected from any of the guests who connect, so that nothing can trickle over.

I had another thought which may not be the most intelligent but I was thinking if the aruba ap's were left on the seperate internet connection and I already have openvpn setup on the PFSESNE for remote connection; could I setup a vpn tunnel for the one ssid's to the PFsense router to access the internal network, would that be the safest way to keep the internal networks data safer?


I am not sure the best way to execute this. If there is an easier and more efficient way please let me know

thanks
0
Hi,

My router not connect to the internet VDSL. DHCP not workint too(the principal problem).  
The command "ip route" not exist!
Configuration:

CISCO881-SEC-K9
ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)

Running:


Current configuration : 1856 bytes
!
! Last configuration change at 14:20:53 UTC Wed Feb 6 2036
! NVRAM config last updated at 14:21:01 UTC Wed Feb 6 2036
! NVRAM config last updated at 14:21:01 UTC Wed Feb 6 2036
version 15.1
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
enable secret 4 tnhtc92DXBhelxjYk8LWJrPV36S2i4ntXrpb4RFmfqY
!
no aaa new-model
!
memory-size iomem 10
crypto pki token default removal timeout 0
!
!
ip source-route
!
!
!
!
ip dhcp pool DSL_DHCP
 import all
 network 10.0.0.0 255.255.255.0
 dns-server 189.40.220.41 8.8.8.8
 default-router 10.0.0.1
!
!
ip cef
ip name-server 189.40.220.41
ip name-server 8.8.8.8
no ipv6 cef
!
!
multilink bundle-name authenticated
license udi pid CISCO881-SEC-K9 sn FTX1648819M
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0
 no ip address
!
interface FastEthernet1
 no ip address
!
interface FastEthernet2
 no ip address
!
interface FastEthernet3
 no ip address
!
interface FastEthernet4
 description DSL interface
 no ip address
 duplex auto
 speed auto
 pppoe-client …
0
I've been having strange DNS issues, and poking around through the registry of the new DC, I found entries of the old DC that still seem relevant to current settings.
It is in HKLM\System\CurrentControlSet\Services\Microsoft\WindowsNT\CurrentVersion\DNS Server\Zones\18.168.192.in-addr.arpa
Registry entryThis server 192.168.18.12 is no longer carrying the DNS role, or AD.
I came to this by way of BPA , in which this server was listed in the servers to be Notified in the "Notify" options.
Either related or unrelated, my DHCP Bindings list is empty for some reason, but appears to be handing out addresses normally.
DHCP BindingsIs this registry entry significant?
Is the DHCP binding issue related and fixable? (The DC with DHCP has a static address...)
0
I need some help. I have a client that has moved into an office and is sharing their space. There is cat5e structured network around the building. There is a router with DHCP turned off providing the buildings owners with an internet connection to their network. What I want to do is connect my client's existing switch and windows server 2012 essentials r2 server (which is both a domain controller and a DHCP server) to the existing router (building owner's router) so that I can share the internet connection to my client. Essentially I will break out all of the ports on the network that my client will be using and connect to my client's switch. That switch then connects to my client's windows server. The existing network and all settings work just no internet connection. The server has two NIC cards if that helps at all. The building owner runs their own windows DHCP and domain controller server. Essentially the only physical connection between the two networks would be through the building owner's router. The router does have available ports. Any suggestions?
0

DHCP

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).