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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Dear Experts,

 We are setting up a Site2Site VPN between Meraki Firewall MX64W and an ASA 5510 firewall.

First time I do this.

I am not sure how to add the Meraki network peer address in the ASA firewall. All the VPNs I have here are pointing to public static IP addresses. The Meraki is DHCP. I only see that dashboard address that I wonder if I could use.

Any useful documents you know of for this task?

Thank you
Hello I created a new DHCP server and now it pulls multiple bad IP addresses inside the address lease. Can you please help assist why it would pull multiple bad IP address for one device aka phone, computer.
I have a Mikrotik CCR 1009-8G 1S-1S+ and 5 Cisco Switches WS-C2960-24TC-L that were provided by the customer for our use in this network. I have a question on how to setup the VLANS so no Tenant in the building can access any other Tenants network. There is a mix of Static IP tenants and DHCP Tenants. I have the Mikrotik Setup with all the needed VLANS for each DHCP Tenant. I have also assigned each port for VLAN access to only one Tenant. My issue is how to secure the VLANS.

I know this is a vague description of what I have to work with so I have attached a PDF of the network. If any other information is needed please message me and I will attempt to comply.

Thanks in advance for any and all help.

Hello Experts,

I am trying to design WLAN solution in open facility, due to cabling\connectivity issue following proposal is provided:

Assume a lager circular facility and outdoor APs (around 120 aps) need to be installed at peripheral.

 we don't have POE option and to install multiple switches thus I need to validate following solution will work?

1.  run fiber across the periphery.
2. connect fiber end to Switch and trunk it with vlan 10, define dhcp scope for vlan 10
3. splice fiber across the periphery at AP connectivity point.
4. use fiber to Ethernet converters.
5. we can use external power injectors.

would appreciate your help in validation.

I have a windows 10 computer picking up a suspicious Gateway, DHCP and DNS IP addresses when I do a Ipconfig /all.   What caused me to investigate was the windows 10 computer would lose connection to our mapped network drives.


G.W   > should be
DHCP:  > should be

DNS: and    > should be

arp lookup on shows a MAC address for a H.P device.

Any thoughts on this?
I have mikrotik 951
I have internet router with ip  and the mikrotik ip Is I add a route to with pref also i have dhcp server on that give the client getaway and dns  as to point it to mikrotik.
till now the internet work on the client without any problem.
when i try to add a hotspot the internet stoped , the client login but no internet.
please note that i setup the hotsport from wizard. and also i disabled the dhcp server after that
so where is the problem ?
I have a Draytek Vigor 3900 device that I have set up a VPN service to allow staff to connect when they're not in the office.
After something of a battle, I managed to get LDAP authentication working, so that the VPN checks that a user is in a particular security group and that controls their access.

I've hit an issue at the last though, that I simply cannot fix.

Some users can log in and some cannot - the Draytek error logs reveal quite clearly that those who cannot log in are not being issued an IP address so the tunnel is dropping.

I cannot understand why they're not getting an address though, when other users are

For the avoidance of doubt, I'm changing nothing except the username and password when I'm doing this, so there are no other variables and the Draytek is logging

Vigor: pppd[16900]: DHCPC: Ignoring XID ab9059ed (our xid is 125a6928)

According to Draytek the XID should be the same, but they don't know why it wouldn't be.

We're a Server 2012 environment, with 2 x DCs in failover mode (that is working as far as I can tell - I paused the services on each one in turn and tried to login - got the same error.

I'm really stuck now, any thoughts or advice welcomed.
hello experts
i need via command to configure my window 2008 R2 DHCP server option 121, but i got the following error so it not works, could you help on this how to do this correctly?
thank you

C:\Windows\system32>netsh dhcp server scope set optionvalue 121 binary -NetworkAddress -SubnetMask -GatewayAddress

Changed the current scope context to scope.

DHCP Server Scope Set OptionValue failed.

Parameter(s) passed are either incomplete or invalid.
The original IT people started using the subnet. I am in the process of migrating to a new server. I set up the DHCP Server with the same scope but when I look at a workstation that received a DHCP address it is telling me the subnet mask is which is not correct. It should be but I can't find anywhere in the DHCP server to set the subnet mask it passes out. Can someone clue me in?
Dear Experts

We have a network of less than 15 systems with 2 broadband connections from 2 different ISP's.
1. ISP1 in their provided router configured the network of and their provided router ip and function's as DHCP server in the LAN
2.. similarly ISP 2 also configured in their provided router with network of and their provided router ip and this also funcationing as DHCP server in the LAN.2
Both the routers of both ISP's are connected to the same switch at the present I have turned off ISP 2 router to avoid 2 DHCP in the LAN.
3. have linux server working as internal private DNS
As per the experts exchange experts advice I am in process of procuring the router with 2WAN port so that each one of the ISP will be connected to one of the WAN port and will stop DHCP service on the router level and will configure DHCP server in linux server. I would like to divide the network of to 4 subnets, as following
a)  of ip range 1 to 62
b) of ip range 65 to 126
c) of ip range 128 to 190
d) of ip range from 193 to 254

attached DHCP configuration, request to please review the defined 2 subnets statements in the config
Soution design and suggestion for the below please:
in this dhcp server the defined 2 subnets i,e access point-1 to one of the subnet of above a) i,e  of ip range 1 to 62 and access point-2 to another …
What is the best way to migrate sbs2011 std to server 2016 std.
Step by step directions!!

I imaged my sbs2011 into hyper v and created a new 2016 server std guest to migrate all the roles, AD, DHCP, DNS to the new server.
Hi all,
I would like to reserve an ipadress + add a host name etc on my DHCP server based on a mac address using PowerShell (of course)
Could you help me ?
Dear Experts

We are in process of setting up very small IT infra where local dns (private dns server) be done on ubuntu server16.4.4.  We will be hosting web based application server in on-premise and for the internet we have 2 service providers  both are of different,
1.  ISP 1 provided device enabled with the dhcp service for the network and it is ON with the subnet of  this is more stable connection
2. ISP2 also provided device and enabled with DHCP service for the network and they are asking to turn it ON -
purpose of 2 service provider is to have backup when one is down operation can happen with other service provider
As of now I have not yet turned ISP-2 modem/router ON as this will also function as DHCP server and in a network 2 DHCP server cannot be enabled.
Please suggest the best practice
1. Should I have to ask ISP-2 to configure for different subnet like and configure one DHCP server in linux server define 2 subnets here and stop both service providers ISP-1 and ISP-2 modem/router DHCP service but when the clients systems boot which subnet to be released as ISP-1 may be down and but the DHCP server release the IP of subnet ISP-1 , how to switch here to another subnet - NOT sure if this is good way to go with please suggest
2. stop dhcp service of ISP-1 and ISP-2 devices and configure dhcp server in linux but with one subnet only but segment the ip range for ISP-1  router and gateway sections pointing to ISP-1 in dhcp …
I'm needing some information about Radius 2016.  I'd like to create a radius server 2016 for mac authentication for wired computers.  The idea is instead of managing this via the switches/routers to manage the MAC addresses via the radius server. I want to basically have users on DHCP but 1st authenticate via Radius.   Can this be done?  And can someone point me in the way of directions?
I have a client who has an older Canon ir2016i Copier.

They have moved into a new office with the copier left from the previous tennants.  From all reports the copier worked fine, but I am unable to get the copier to get an IP address from the modem.
I am wondering if anyone knows a way of factory defaulting the machine or any other tips to get the copier to seek an IP address.

I have tried DHCP and Static IP functions.  I have also connected the copier direct to the modem instead of through the new network cabling installed.  Both to no avail.

The copier can photocopy fine.

I am going to try the USB connection today but would prefer a network connection.
Dear Wizards, is it possible for a DHCP pool was deleted automatically? How can I check the log for that? Is it possible to check the historic commands on switch when the ssh connection was turned off? Many thanks.
- (1) Cisco SG250 26P PoE switch
- (2) Ruckus WiFi ZoneFlex R610 access points (using their Unleashed setup)

I'm about to create/implement my first VLAN's, I'm pretty stoked I finally get to play with VLAN's. I've been doing IT/networking since 1991 but never did VLAN's. I've configured Sonicwall firewalls from scratch but this is my first Cisco device I get to admin; thankfully it has a GUI. I've already researched the heck out of VLAN's, trunk ports, tagging, & more, & I feel I'm ready to do it. I have the freedom to create this new network as if it were the original network built for this office. Almost all the employees are out of town for next week so it's an ideal time to build a new network. There are no Windows servers or any network services on this WiFi network; all that stuff is on the "corporate" network. This WiFi network I'm replacing/upgrading is what could be referred to as a "rogue" network that this department installed themselves just so they'd have faster Internet.

I'm creating VLAN's so our business can separate the Guest WiFi traffic to its own VLAN but also allow some inter-VLAN routing to allow our screen-sharing solution (Airtame) that guests will be using to talk to our big screens in the conf rooms, which will remain on our internal/business VLAN.

We currently have a Netgear Orbi Pro WiFi network setup but that's not quite robust/sophisticated enough for what we need to do. I'm keeping this existing Orbi WiFi network hardware …
DHCP configure failover failed error 20010.  Primary DC/DHCP/DNS Windows 2012 server comes up with error when i configuring dhcp failover. The other server is Windows 2012 R2. I did google search and found few suggestion but none helped. I have shoretel custom defined option that is also entered in 2nd dhcp server but still gives an error. Any idea? Thanks!
Running a HYPER-V host (Windows Server 2012 R2 Data Center), with 11 vm's connected via NIC Teaming connected to an Aruba 2920-48G Switch, 3 of the vm's are suddenly not able to connect (yellow explanation sign reads 'no Internet connection'). NIC cards shows no issues and NIC Teaming has all green up arrows. No issues in the event logs.

I removed the static IP's from the servers but they still won't connect to DHCP (with error 'unidentified'
I deleted the virtual NICs and recreated (same issue)
I checked DNS and there are no issues jumping out at me
I replaced all of the Ethernet cables on all NIC's on the server
I logged into the switch and didn't see any issues

I have never seen anything like this. Is there another area that I should be looking at? My fear is that more servers will lose connection and I am at a loss as to why.
Can I just change an IP address of a AD server easily?

I set up a new AD server that is running DHCP and DNS to replace an aging server, but I want to clean up the IP addressing. Here's what I have:

Aging server IP:
New server IP:

So I set up the new server while the aging server was still running, but now the new server is handling DHCP and DNS requests, it's time to retire the old server. Once I demote the old server and retire it, can I just reassign the new server's IP address to the old one and give it the .2 address? Or is there something else I have to do to change addresses for an AD server?
I'm working at integrating Mitel 6867i phones into our network.  
At first, the provider said that there had to be firewall ports open (and, obviously NOT forwarded to any particular IP).  That is, the ports had to be opened incoming and outgoing.
Well, usually outgoing is open by default.  So that would only be mentioned to CYA.
And, if outgoing is all that's needed then saying incoming is needed seems double CYA.
My hope is that no firewall ports need be specifically opened at all.  

But, I started on this path by accepting what they specified and decided I would NOT run these things through our main firewall at all.
So, there will be a separate firewall as we have enough public IP addresses to accomodate.
And so, there has been a VLAN set up just to service the VOIP phones and to keep the firewall LANs separated.

I hope this much sounds like a reasonable approach.

If you're familiar with these phones (and I hope you are) then you'll know that the phones will accept a trunk line connection and "pass through" the main LAN / e.g. VLAN1 untagged to the computer on the desk.  (This saves running a new cable to the desk assuming the computer is already cabled).  And, the phone functions are supposed to run off a tagged VLAN / e.g. VLAN100 that's combined on the trunk.

All this seems fine so far.  I'm a little uncomfortable with the phones being so integrally connected inside the network but it seems like accepted practice.

As they say, "the devil is …

I've mostly used combination modem/routers in the past so I hadn't really come up against this till now. I have an ADSL modem which serves DHCP, but only to one device. It also doesn't have a configurable IP. I plugged my router into it (connected to the WAN port, of course), but when I do that, I can't use the same subnet on the LAN as on the WAN. (The modem serves 192.168.1.x, so I have to use something else, e.g. 192.168.0.x.)What I don't understand is why those can't be the same. Aren't they separate networks? Doesn't the router's NAT take care of stuff like that? Is this just an arbitrary limitation of this router, or is there some reason it must be this way?

Doesn't that create a problem in the way things are modularized? For example, when I was first configuring my router, I had the modem disconnected, and I was configuring it on 192.168.1.x. As soon as I plugged in the modem, it changed my LAN subnet to 10.0.0.x. This leads to the situation in which, if I switch out the modem, and it decides to serve some subnet supposedly "in conflict" with my LAN, my whole LAN is screwed up because it's dependent on some modem which isn't even on the LAN. Likewise, it makes for a restriction in the way I can configure my LAN, based on some silly modem that isn't on the LAN.

Please help

I didn't find the right solution from the internet.


DHCP server shows up internal ip address as 169.x.x.x which seems incorrect since it should show up as internal 10.x.x.x for nic card on server.  I tried resolving the secondary dns server under scope options and it resolved it as correct 10.x.x.x but the primary dns was resolving to the 169.x.x.x address.  Does this sound right?  We have been having disconnects in the office to the internet as wells as remote users logging into the remote desktop server getting disconnected so we are not sure at this point if there is any correlation between the dhcp/dns issues and the internet disconnects.  I would think if users get kicked out of internet sessions both going out and coming in then it might be the router.  Any ideas?  thanks
I have a DHCP scope that is running out of ip addresses. The ip addresses are 192.168.1.x with a /24 mask and with limited number of ip addresses (of course). I have another scope we don't use or need (ip address range is 192.168.2.x with a /24 mask I would like to combine the two. Is that possible? If so what is the process to combine the two scopes into one scope?

I have two different Domain controllers with two different domain name, (xx.com 10.0.100.x and xxx.com 10.0.100.x) but ind the same IP range one with an active DHCP server and another with a ready to use but not started DHCP server.

My senario now is to shut down the DC with the active DHCP (xx.com) and start the DHCP up on the other domain controller (xxx.com), but I got an error "Scope or superscope is inactive."

Can anyone tell me what could be wrong, have I forgotten something?

I have checked that the DHCP is active and running







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).