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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Hello - I have a Security Device Scope set on my DHCP server.

10.201.192.20
10.201.207.254

255.255.240.0 /20

What I want to do is assign another scope within my Security Device Scope for 10 Camera, 10 Card Readers and 2 Media Servers. How would I break that scope up into other scopes for the following devices, however using the Security Device Scope?

Thanks,

nimdatx
0
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One of a set of tools we're offering as a way to say thank you for being a part of the community.

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
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
I have a task assigned to event id 1020 (windows 2008 r2) to send an email when a dhcp scope hits 80% usage.  It had been working fine before when usage was high, but now it is showing that a particular scope is over 80% used when it isn't.  When I look at the scope statistics, it shows there are 41 (82%) addresses in use with only 9 available.  However, when I refresh the lease list, there are only 17 addresses being used, not 41.  How is this possible?
0
Hey guys. I need some help for... a friend. (It's a Monday. Please don't ask)

Environment:
2 Domain controllers running Server 2012 Datacenter
Veeam BR 9 on Server 2012 Datacenter

Leadup to issue
DHCP scope was acting funny... a few tinkerings later and the entire service was hosed. A restore of that DC on Veeam and now the entire sync between both DCs was not working, even after attempts to get them synced (dcdiag, repadmin, etc.).

A restore of both DCs to the same backup time should work, right? NO. Veeam restores DCs into non-authoritative mode...

Current situation:
DC1 is restored from Friday night's backup but shut down for now. Attempts to log in with DSRM password failed. (Just great, right?)

DC2 is running and serving DNS, AD, etc. but it fails dcdiag tests:
-time server advertising
-DFSREvent
-KnowsOfRoleHolders
-Replication attempts (obv.)
-RidManager
- etc (too many to list)

Question/Request:
Before my uhhh... friend breaks anything else, just throw me in the right direction. He's a little out of sorts and just needs to be reminded what to do at this point.
I would tell him to do a non-authoritative restore of DC1 and let DC2 be "the boss", but both servers were restored from Veeam in non-authoritative mode and the DSRM password isn't working. Attempts on DC2 to change the password failed. Yaaay!
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.
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Hello -

I presently have a CIsco ASA 5505 (running ASA version 8.2(1) ) sitting behind my Comcast Business gateway. I have a static public IP through Comcast. The Comcast gateway is in pass-through mode (i.e. its LAN DHCP, WiFi, and MoCa are turned off).

I have configured my Cisco with the necessary VLANs and interfaces such that I have an inside network of 10.0.10.xxx and a DMZ of 192.168.10.xxx.

I am fairly certain that I have the correct NAT and ACL settings done.

From the ASA, I can successfully ping my Comcast static IP and the Comcast gateway address - but nothing else. And, of course, any client devices connected to either the ASA's inside interfaces or DMZ cannot access the Internet.

FWIW, I have also checked with Comcast to make sure there are no compatibility issues with their device and Cisco ASAs (because I'm only getting an orange LED on the Comcast gateway's Ethernet port - no green link light). The ASA is set to auto duplex and speed.

If I configure a laptop with the static IP and plug it directly into the Comcast gateway, it works fine.

I have attached a text file with my ASA configuration.

Can anyone suggest a possible fix?

Thanks much.
ASA5505_Config.txt
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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.
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Dear All,

We have internet and intranet are separate on physical layer due to company security policy. We are using DHCP for ip release on both intranet and internet. At times user use the intranet computer on the internet by unplug the intranet cable and plug the internet which we do not want. To avoid this we have configured the static ip on the intranet computers and minimize the privileges to change the IP. Through this the user can not use the internet on the intranet computer due to non release of ip address.

My question is is there any way through firewall or Windows Active directory through which our intranet user cannot connect to internet on the intranet computer using dhcp. In other word , can we limit the user not to connect to internet.
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I am setting up my hardware firewall to issue DHCP IPs and associated DNS servers (8.8.8.8) instead of having my Windows 2012 R2 server do DHCP

 1. What method do you recommend I use when decativating DHCP on my Windows 2012 R2 server ?
         a. stop the DHCP service OR
         b. uninstall the DHCP role OR
         c. click "Deactivate" via the DHCP console like https://technet.microsoft.com/en-us/library/dd183590(v=ws.10).aspx talks about

 2. Do I need to do a release/renew on all non-static devices (i.e. a few switches, a few PCs, etc) after doing this so my firewall does not issue IPs that were already issued via the Windows 2012 R2 and have leases that are not expired yet ?

 3. Anything else I need to know ?
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Need another pair of eyes to check my DC specs.  Mostly for AD purposes box.  DC, DHCP, DNS.  Maybe Print server as additional.  I will dial another DC on VM.  

Win2016 DC
FT-E5-2603V4, Intel Xeon E5-2603V4 1.7GHz 1U
Including:
* (1) Intel Xeon Processor E5-2603V4 Haswell (6 Cores)
* (1) Supermicro Motherboard X10SRW-F
* On Board Dual 1GB NIC Ports
* On Board VGA
* On Board IPMI 2.0
* 16GB DDR4 2400 RAM ECC/REG Installed, Lifetime
Warranty
* (1) Riser Card w/ 2x PCIe x16 GEN 3.0 FHFL
* (1) Riser Card w/ 1x PCIe x8 GEN 3.0 LPHL
* (1) LSI 9271-4i RAID Controller
* (2) 1TB Enterprise SATA 7200RPM 3.5" HDD
* (4) Hard drive Bays for 3.5" or 2.5" as an option
* (2) PCI-e 16X GEN 3 Slots available
* (2) 500W Hotswap redundant PSU
* (1) Microsoft Windows Server 2016 Standard Operating System
64-bit English (16 Core), OEM
* 3 Years Full Warranty w/ advance ship replacement
1
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
Hello Experts!

I have a 2008 R2 domain running with 2 domain controllers, a virtual 2012 R2 instance (named DC1) and a physical 2008 R2 server (named FS1).  DC1 is also part of a DHCP server team.

Lately, I've seen a number of my workstations (most Win7 Pro) begin to exhibit long delays during the logon process, in addition to long delays in response from our ERP system clients.  Looking in the event logs showed NETLOGON Event ID 5719 (no logon servers available to service the request) and Group Policy processing failures with Event ID 1055 (Name Resolution failed or there is an Active Directory Replication issue).  The computers eventually become responsive, although users report numerous hang conditions during the day.

Troubleshooting the two domain controllers led me to notice that the DNS BPA was failing on both DCs with the following error:

'This domain controller must register a DNS SRV resource record, which is required for replication to function correctly.'

To try to better understand what is happening, I ran DCDIAG /test:DNS on each DC, and both returned the same errors:

 TEST: Records registration (RReg)
                  Network Adapter [00000010] vmxnet3 Ethernet Adapter:
                     Error:
                     Missing SRV record at DNS server 192.168.2.32:
                     _ldap._tcp.97f4b9f2-b245-4088-9d3d-e6a9cd559a95.domains._msdcs.jd.local

                     Error:
                     Missing SRV record at DNS server…
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
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
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Veeam Disaster Recovery in Microsoft Azure

Veeam PN for Microsoft Azure is a FREE solution designed to simplify and automate the setup of a DR site in Microsoft Azure using lightweight software-defined networking. It reduces the complexity of VPN deployments and is designed for businesses of ALL sizes.

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
I am using an older Cisco ISA500 router, and a SF200-48 Smart Switch and an SG110-24 dumb switch.

I have GE3 on the ISA router configured as 192.168.3.0/24 (VLAN ID 3, PCI network) which is uplinked to the SG110-24.
I have GE6 on the ISA router configured as 192.168.2.0/24 (VLAN ID 1, non PCI network) which is uplinked to the SF200-48.

The scenario is that this is a grocery store, and all of their POS equipment is plugged into the SG110-24 24 port dumb switch uplinked GE3 on the router which is configured for VLAN ID 3 for PCI compliance.
 
We have two UniFi APs that are plugged into ports 24 and 48 on the SF200-48. I have ports 24 and 48 on this switch untagged for VLAN ID 1 and tagged for VLAN 3.

I have two SSID's configured on these UniFi AP's.. one for the store network that issues out DHCP addresses from the default VLAN 1 network which works fine, and one for the PCI network that should issue out DHCP addresses on the 192.168.3.0/24 subnet, however,I am not receiving an IP address via DHCP when connecting to my SSID tagged to VLAN 3 on my access points.
 
Can someone tell me where I'm going wrong? I don't really have any experience implementing VLANs.
If I plug directly into the SF110-24, I am getting an IP via DHCP on the 192.168.3.0/24 subnet so DHCP is working for that VLAN.
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 Guys,

I am playing around in my lab making sure I can do what I need to do for a job I have coming up. I have a 3750 and a 1941 to play with and a bunch of ip phones. The practice was supposed to ensure I can configure the switch to assign correct VLAN to cisco phones and ensure that the data port on the back of the phone is assigned to the correct VLAN also. However that aside, I have found since configuring the data vlans and assigning my wifi access point to the vlan that the internet is flakey. I mean it works however some sites just don't, when I do a speedtest.net check, it takes forever to execute the ping test however then does the transfer which is fine. I have another Wi-Fi access point that is not vlanned or going through the 1941 however using the same internet gateway and it works flawlessly.

I have configured two VLANS on the switch, I have one switch port configured for trunking passing the two vlans through to the 1942 for gateway and also DHCP.


My 3750 config:


version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname my01suj01sw01
!
enable secret 5
enable password
!
username root privilege 15 secret 5
aaa new-model
!
aaa session-id common
switch 2 provision ws-c3750-24p
system mtu routing 1500
vtp mode transparent
ip subnet-zero
ip domain-name rancho-relaxo.com
!
ip ssh time-out 60
ip ssh authentication-retries 5
!
!
!
!
!…
0
my Cisco router 881 does not provide ip address to ports thru vlan after configuring the DHCP pool
when i made the configuration at first time it was working after erase it stopped. if ip assigned manually to pc  it works.
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

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).