DHCP

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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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Not sure if I have setup QoS for VOIP correctly to interact with RingCentral on my switch.

I know almost nothing about this aspect.  Switch is Aruba 2540.

RingCentral is seeing jitter when they diagnosed it, I want to make sure that the switch is prioritizing the voip traffic at the best priority over data but I have no idea if this is the right way to do it, or if there is a best-practice type of approach?  The phones are on vlan 10, phone plugs into switch, pc plugs into phone, PoE is used.  In this instance I just want to confirm the switch is properly configured to prioritize traffic, if the problem is upstream, it's upstream, I am just concerned about the switch at this point.

I don't know what the dscp mapping table looks like so maybe ultimately I'm missing the priority?

hostname "zzz"
module 1 type jl356a
qos type-of-service diff-services
ip default-gateway 192.168.xx.xx
ip route 0.0.0.0 0.0.0.0 192.168.xx.xx
snmp-server community "public" unrestricted
snmp-server contact "zzzzz" location "zzzzzzz"
vlan 1
   name "PCS"
   untagged 1-28
   ip address 192.168.xx.xx 255.255.255.0
   exit
vlan 10
   name "PHONES"
   tagged 1-24
   ip address 172.168.xx.xx 255.255.255.0
   ip helper-address 192.168.xx.xxx
   qos dscp 101110
   voice
   exit
no tftp server
no autorun
no dhcp config-file-update
no dhcp image-file-update
no dhcp tr69-acs-url
password manager
password operator
0
When I setup a new server is it better to have dhcp and DNS running off the router instead of the server.

The reason why I ask is if the server ever goes down they will still be able to have internet.

Especially if our client is far away.
0
Receiving a ton of "who has 10.0.30.30? Tell 10.0.30.1"
30.1 gateway
30.30 first IP in dhcp pool.
IP has not been assigned in scope (its available).
Wireshark showing broadcast source of gateway SG300-52P.
However SG300-52P arp table has no reference (guess that's obvious from the packet info).

Not sure how to find where this request is coming from and/or how to turn it off.
0
I have a simple network, all flat, using default vlan 1 on my LAN.  I do have 2 switches that have a different vlan to separate my camera traffic.


I am implementing 2 more switches, stacked, (vlan 90) that I need them to be able to access the rest of my current network, vlan 1.
I'm going to create the new vlan on the core switch and add an IP address to it.  I know that all my uplink ports need to also be trunk ports,
so it can pass all the vlans,  I'm guessing, all I need to do is add the new vlan on every current switch in my network and that's all I have to do from a
networking standpoint.  I also need to add the IP helper command on my core switch, so I can pass the DHCP info to my DCs.  Am I missing anything else
I need to do?

In regards to my AD, I'm running windows server 2012R2 for all 3 of my domains.  I'm running DHCP and DNS.
So I'm assuming I need to create a new lookup zone for this new vlan and IP range.
Besides that, am I missing anything?  What else would I need to do?

Is there anything else I need to do to make this happen?

vlans
0
Hello everyone,
Today we worked on installing a new server at an office that has around 50 users.  We planned out and deployed a server migration from Server 2008 R2 to Server 2019.  

All worked well, FSMO, DHCP, DNS, everything moved over without a hitch.  After modifing the login script to recognize the new file server, all users were able to login without any problem and access files.

That all changed about an hour later.  A network connection was disconnected from the new server.  And ever since then, the computers have slowed to pas a crawl.

Like it literrally takes 15-20 mins just to LOG IN!  
Once logged in, you simply can't click any applications or even the start menu.  They aren't locked, just every operation takes minutes when they should be mili-seconds.

I started investigating.  One issue I found was the GPO objects didn't move from the old server.  So when I tried to modify them in the GPO manager, it gave errors saying it couldn't be found.  So I copied them out of SYSVOL on that old server.  Great.  I was now able to edit those GPOs.  

I cleaned up some DNS entries, but I cannot find anything in the event log of any of the servers to indicate any problems.  Since the workstations are soooooooooooo slow, I can't even open the event viewer to see what is going on.  Every command I send it, times out.  I can't find any errors in DNS or DCDIAG.  

Please help
0
Is it a good idea to have an SCCM distribution point serve as a DHCP server as well?   Why or why not?
0
Hey everyone - I am trying to get my router up and running and having a slight issue getting it to connect the internet ( to the ISP ). My basic idea is connecting G0/0 going out to the ISP (Wan), G0/1 to my server. I know im missing something. I've included my running config.
Any help would be appreciated!!

Current configuration : 1735 bytes
!
! Last configuration change at 16:01:56 GMT Tue Jan 21 2020 by admin
version 15.1
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Core_Router
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
clock timezone GMT -8 0
!
dot11 syslog
ip source-route
!
!
ip cef
!
ip dhcp excluded-address 10.24.1.1 10.24.1.10
!
ip dhcp pool core
 import all
 network 10.24.1.0 255.255.255.0
!
!
ip domain name xxxx.net
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
voice-card 0
!
crypto pki token default removal timeout 0
!
!
!
!
license udi pid CISCO2821 sn FTX1311A0C3
username admin privilege 15
!
redundancy
!
!
!
!
!
!
!
!
!
!
interface GigabitEthernet0/0
 description PrimaryWANDesc_
 ip address dhcp
 ip nat outside
 ip virtual-reassembly in
 duplex auto
 speed auto
!
interface GigabitEthernet0/1
 ip address 10.24.1.1 255.255.255.0
 ip nat outside
 ip virtual-reassembly in
 duplex auto
 speed auto
!
interface FastEthernet0/1/0
 no ip address
!
interface …
0
I want to connect a fresh Meraki switch to a Cisco ISR. By default the ports on the Meraki are native VLAN 1 and type Trunk. If I make the native VLAN 10 on the ISR's port attaching to the Meraki switch that would create a native VLAN mismatch - but still the two devices should be able to talk to each (assuming I have a DHCP scope on the ISR for VLAN 10).

If I have an ISR (say 4331) configured with inside trunked interface as follows:

Hostname(config)#interface FastEthernet0/1
Hostname(config-if)#no ip address

Hostname(config-if)#no shutdown

Hostname(config)#interface FastEthernet0/1.1
Hostname(config-if)#encapsulation dot1Q 1 native
Hostname(config-if)#ip address 10.10.100.1 255.255.255.0


Hostname(config-if)#interface FastEthernet0/1.2
Hostname(config-if)#encapsulation dot1Q 2
Hostname(config-if)#ip address 10.10.200.1 255.255.255.0

ip dhcp pool MGT
 network 10.10.100.0 255.255.255.0
 default-router 10.10.100.1
 domain-name acmefoo.com
 dns-server 8.8.8.8 4.2.2.2
!
ip dhcp pool DATA
 network 10.10.200.0 255.255.255.0
 default-router 10.10.200.1
 domain-name acmefoo.com
 dns-server  8.8.8.8

The meraki should pick up an address from DHCP for VLAN 10 10.10.100.0 owing
to the fact that those frames would be untagged despite the fact that the default
native vlan on the Meraki is on. Correct?
0
Hello,
I would like to ask why a client sees in network card details that the lease of ip address is less than 2 hours, while in dhcp server (windows server 2016), it is set up for 6 days, the lease period.
Thank you
0
I am setting up a new Windows 2019 Server for a customer.  The way I was taught in the past was to add the role of DNS server to the DC and use the router for the DHCP to the PCs.  I have done it successfully on several servers but it seems convoluted and possibly not correct and efficient.  I do have one customer where the DC is both the DHCP server and DNS server and have not had any issues.  The DNS is configured properly with the interfaces and forwarders and DHCP turned off in the SonicWall.  DHCP is configured with the scope and all of the correct parameters.  I would like to get some opinions as to which way to go.  It seems to me it would be best practice to allow the DC to do both.  What are the pros and cons (if any) using this method?
Thank you in advance,
Phil
0
DHCP  for Wired and Wireless Devices

I would like to have an Expert explain the path Wired and Wireless devices take to get IP address from DHCP  


I put a diagram below, it might not be the right path that devices take to get IP address, but it can be corrected by an Expert.


Thank you


d
0
SBS 2011 standard to Windows Server 2016 Essentials migration
Microsoft's docs recommend to move the DHCP funtion to the router.
Is there a good reason for this as opposed to moving it to the 2016 server?
Has anyone had favorable/unfavorable results either way?
If on 2016, can the existing scope/parameters be moved easily from SBS?
0
Hi Experts,

after DHCP migration, all WIFI clients do not get any IP.
But over LAN it works.

Here is the error:

PTR record registration for IPv4 address [[172.23.22.111]] and FQDN PC1-NB001.wittur.com failed with error 9005 (DNS operation refused.
).

Open in new window


The DHCP is not on DC.
It is installed on another server.

Any ideas ?
0
Hi Experts,

I like to migrate my DHCP config to another server.
The old config is on Server 2012 R2
And my new Server is Windows 2019 Core.

Is this possible ?
Please can you show me the commands ?
0
I picked up a couple of the new Linksys Business APs that allow VLAN Tagging and I am having fits getting the VLANS on the switch configured properly to get these APs to work. There are currently 3 VLANS on the switch:

1: Management, ports 1-28, port 1 goes to SonicWall
2: Guest, ports 29-34, port 29 goes to SonicWall
3: Printers, ports 35-44, port 35 goes to SonicWall

Each port on the SonicWall is a different network and does the rules between networks. It is also the DHCP for each network. So... what I was trying to do was put these APs on the Guest network and if I were to tag a specific SSID with VLAN 3 it would give the clients on that SSID access to printers.

So what D-Link told me to do was to tag port 35 and share it with the Guest VLAN. So when a client on that specific SSID (tagged with VLAN 3) came in to VLAN 2 it would immediately pass the packet to VLAN 3 and in turn give it access to printers.

When I did that the management VLAN could no longer avvess printer. What a mess. It seemed so simple. Any ideas on what I am missing?
0
I have a windows server 2012R2 for DHCP and DNS.

I am reviewing my reverse lookup zones in my DNS server and I have a lot of computers in there with the same name, but with different IPs.
What is the best way to clean it up?  Can I just delete every entry for every reverse lookup zone?
0
Went on a call to a new client today, who has been having issues with their network.  They have a DSL modem with WiFi on channel 1 (Since disabled) cascading to a TP-LINK Archer c5400 (Upgraded firmware today).  They are working on getting the PPPoE (Centurylink DSL connection) so we can bridge the DSL modem and set the router up properly.  Some devices hardwired and wireless will not function because they are getting a DHCP address from the DSL modem.  I can log into the DSL modem on those computers.  Is this a malfunction in the TP-Link (It only happens less than 10% of the time and very random on devices)?  I have had very bad experiences with TP-Link switches, are their routers any better?  The owner said the problems have always been existant and the old IT company (who installed it), could never get it working 100%.  I am recommending replacement of router, but wanted to hear thoughts on this subject.  The client will be ordering their own new router, and won't have until Monday.  This should be a non-issue once the modem is bridged.

If I release the DHCP enough times, it will go back to the correct DHCP server of the router and start working properly.  The DSL modem is not accessible by devices connected when getting the working IP address.
0
I'm experiencing a new crazy issue.  I have about 9 MAC computers on a network with mostly Windows PCs.  I have a windows 2012R2 DC, with AD, DNS, DHCP, etc...
If the Macs use a static IP, everything works fine, the hostname stays what is configured by the user.

As soon as I change the manual IP to DHCP on the MAC, after a reboot, the hostname of the PC randomly changes to a windows PC name.
It's completly random, as different MACs use different windows PC names.   Where do I even begin to troubleshoot this issue.

I am running different versions of the mac, on most of the macs, i'm running Mojave.  A few are running Catalina.
0
Dear Experts
We recently decided to implement MPLS connectivity between two locations, the location 1 head office which has ILL (leased line) Cisco FTD on Fire pro 1010 with cisco FMC appliance.
Since it is managed MPLS connectivity service provider has placed their router equipment in both the locations in that port 0 they have connected it to their modem and port 1 we are thinking to connect with ethernet cable to our switchs at  
At branch office
Please suggest at branch location port 1 of the service provider router equipment will be connected to the local switch and same router we have asked to the configure as DHCP server.
At head office
We have connected service provider router to local switch making use of port 1 but here we have windows AD functioning as DNS and DHCP hence service provider router is not configured to function as DHCP server.
1.      Please suggest should the MPLS router to be connected to firewall (CISCO FTD) or is it okay to connect directly to our local switch
2.      Since we are in MPLS network can we think to configure DHCP slave at branch location OR dhcp primary server
3.  please suggest is it recommend to have RODC in branch office, we prefer to join the systems of branch office to domain (windows AD) which is in head office

Branch location IP pool is 192.168.105.0/24 and head office IP pool is 192.168.109.0/24
please help on above 1 , 2 and 3 suggest the best practice design, thanks in advance.
0
New Lenovo Thinkpad laptop with Win10 Pro v1909 connected WIRELESSLY to a home office peer network.

Laptop connected to a NAS and a Unix server with no difficulty, but couldn't connect to any printers. One printer is an HP LaserJet with a static IP address. The other is a is a shared HP USB connected inkjet printer.

Neither printer's installer could see the target printer. The LaserJet was neither pingable nor could I connect to its webserver with a browser.

An older Windows 7 laptop, also connected wirelessly, has no difficulty printing to either of the printers.

The laptop gets it's IP address via DHCP. It's on the same network as all the other devices on, hence its ability to connect to the NAS and the UNIX server.

It's been driving me nuts...then I wa finally able to connect it to the network with a wire. Presto...both printers installed as expected. Went back to a wireless connection and the printers were unreachable again, as expected.

Why? ALL network properties for both the wireless and ethernet adapters are exactly the same. Network and Sharing options all all the same on a Private network.

What am I missing?

Thanks
Mark
0
We have a PC that we have staged with Windows10 pro and enabled Hyper-V
We have set up a Windows10pro VM
The physical host has two network cards.
One set via DHCP
One set with a static IP

There is an application that will run on the VM that needs to communicate with the static IP network card.  
Everything else on the VM can/should go through the DHCP assigned network card.

I've done some sleuthing around the internet, but cannot find or decipher how to achieve this in the network settings of the HyperV.

Any help is greatly appreciated.
0
Hi guy,
I'm configuring a cisco switch (slm2024).
This is what i want to do:

port 5 -> VLAN 10 (LAN)
port 12 -> VLAN 5 (WAN)

On port 12 is connected a ISP modem/router. This router provide a DHCP of private class (192.168.0.X/24)

On port 5 is connected a laptop
I don't understand why laptop is getting a IP from DHCP...it's in a different vlan!
Maybe this issue from vlan1?

This is config

vlan1.PNG
vlan5.PNG
vlan10.PNG
Thanks!
0
DNS and DHCP Interaction

Recently we had to replace old  computers with new ones but we kept the same hostname , the new computers get different IP address than the old ones from DHCP.

Example :

Old ComputerA  replaced and named  the same ComputerA
Old ComputerA IP address: 10.10.10.10
New ComputerA IP address: 20.20.20.20

What I have noticed after replacement:
If I login locally to New ComputerA, and run Ipconfig, I will see 20.20.20.20  which is correct.
If Remotely I ping by hostname the ComputerA,  I get 10.10.10.10 with Destination Host Unreachable. [you can see it looks for old IP address]
if Remotely I ping Reverse lookup : Ping -a 20.20.20.20 , it will Reply properly and shows ComputerA  with IP 20.20.20.20


So the problem seems to be the DNS A record does not get update quickly,  I said Quickly because after sometime, if I go and ping by hostname ,ie : Ping ComputerA, I get a proper Reply with 20.20.20.20

My question is I do not understand why Reverse Ping [Ping -a <IP address>] will Reply quickly and Ping Hostname did not Reply until later time....

Any clarification will be very much appreciated.

Thank you
0
Hi Experts,

we have an in ternatinal network.
Do you know a way, how to determine all my DHCP servers in the whole network ?
0
I am currently investigating on migrating from our current Windows 2012 R2 DHCP and IPAM setup to Windows Server 2019.
A few questions?

Will DHCP 2019 work with existing IPAM server on Windows 2012 R2 or will I need a separate Windows 2019 IPAM server?

If I need a new IPAM server can I have it along side the existing IPAM 2012 server or do I need to migrate or upgrade it?
0

DHCP

10K

Solutions

15K

Contributors

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).