Questions tagged [dhcp]

For questions about DHCP in in relation to network devices. For instance, you are setting up DHCP on a layer 3 switch.

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2answers
73 views

Routing DHCP into different LANS

If I had a router that's connects my 2 LANs and there is a single DHCP, in the either LAN. How and what would be my configurations for the DHCP so that it provides the IPs to both the LANS through the ...
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1answer
155 views

TCP connection question

Let’s say I have 4 ethernet interfaces getting IP addresses via DHCP. I make a TCP connection to a TCP server via one of the IP addresses on a certain ethernet interface. After the connection is ...
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4answers
2k views

Does a router always have two IP addresses?

So I got pretty confused with this question, and while looking online I've found several answers saying that a router does need 2 IP addresses at a minimum, but it isn't clear to me why. Lets say ...
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1answer
148 views

Static Allocation vs Dynamic Allocation [IP Addresses]

Quick question regarding static vs dynamic allocation of IP addresses. I understand that in static IP addressing the address does not change while in dynamic addressing it could differ each time a new ...
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1answer
189 views

How Pppoe subscriber with static ip sends ipcp request

How a pppoe subscriber with static ip sends ipcp configure request. For dhcp the subscriber can include 0.0.0.0 in configure request of ipcp packet and obtain its ip from remote server. But in static ...
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1answer
12k views

How DHCP OFFER unicast works?

In the DHCP discover packet, the source IP address field is 0.0.0.0 which means the client does not have an IP address yet. But, in the DHCP offer packet, an unicast address (which will be allocated ...
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1answer
95 views

What hardware do I need to assign IPs based on port?

Similar (but different) question: Assign an IP address based on switch port I regularly need to test our hardware products. Usually that consists of having ~50 devices sitting on a bench for some ...
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1answer
146 views

How a client behaves if same IP address is assigned to two different interfaces?

First of all, these questions are just out of curiosity. I don't have such configuration, I'm just wondering how a box would behave in such environment. Say we have a Linux box with two network ...
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1answer
944 views

Assign DHCP IP address on Cisco router interface

Hi, dhcp router is configured with following DHCP settings: ip dhcp pool B network 192.168.1.0 255.255.255.0 default-router 192.168.1.1 ip dhcp pool C network 192.168.2.0 255.255.255.0 default-...
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1answer
54 views

What is the use of Manual IP Settings on Copy Machine which is Connected to Router with DHCP

Today, my company got a new copy machine. During configuration, copy machine guy asked me what IP address we want to use for the copy machine. I said, "I'm gonna reserve 192.168.1.200 in DHCP ...
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1answer
815 views

HP 4210G DHCP relay

I have an HP 4210G, which is a rebranded 3com 4200G. I have set up DHCP relay on the switch, but I'm only able to select one server group aka one IP at a time. Is it possible to set up multiple DHCP ...
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2answers
20k views

Devices behind Catalyst 2960 not receiving DHCP addresses

I am having an issue with DHCP not traversing to devices behind a switch. I have many other switches deployed with nearly the same configuration that are able to receive a DHCP address. On this switch ...
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1answer
655 views

Unifi USG gateway

On my firewall "gate protect", I have set one network to use DHCP with the subnet 172.25.112.0/24. After I connect it on my USG pro as WAN and the LAN port goes on the ubnt POE switch there is ...
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1answer
598 views

Help this problem with Dhcp Server with two switches

I will try to explain my problem. I am trying that Switch 1 can give dhcp for pcs but i cannot, in Switch 0 I can give dhcp server in the pcs. sorry for my bad english ROUTER ! version 15.1 no ...
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1answer
9k views

“ssh: connect to host myserver port 22: Invalid argument” (intermittent, ipv6, link-local address, dhcp hostname) [closed]

Since this question is off-topic I moved it to Super User. But I was unable to delete it. Here is the new location. Here is the original question: I'm trying to connect to a headless server via my ...
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2answers
59 views

Advice on potentially needed subnet expansions

I work for a non-profit with some slightly more antiquated hardware. We have 3 locations, about 700 devices across them. Right now our locations are set up as: Location 1 (Main) - /23 with a DHCP ...
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2answers
1k views

Configure VLAN with DHCP traffic properly forwarded

I have a windows DHCP server in VLAN 10 and I have wireless clients in VLAN 288. The VLANs are defined in my Juniper EX-4600 and the VLANs are tagged/trunked all the way to the Meraki APs. [DHCP]---[...
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2answers
446 views

Should an Access Point without internet set the DHCP Offer-Router (3) option?

Wireless device (internet of things device, like wireless printer) creates a wifi network. The device has ip 10.0.0.1 and does not have acces to the internet. The DHCP server on the device sets the ...
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1answer
461 views

Why would my router send an ARP request about a device that's already listed in its ARP cache?

I checked my Ubiquiti EdgeRouterX's ARP table and my laptop IP and MAC address were there. I then checked the DHCP lease and my laptop's IP address doesn't expire until tomorrow. I then ran ...
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2answers
894 views

Does DHCP Client or Server re assigns the IP address?

I know that DHCP protocol ensures that they don't assign an address which is already assigned to another host. This can be true even when the host has been assigned with a static IP address. Also, ...
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2answers
3k views

Why DHCP protocol needs Client ID?

A DHCP request from multiple hosts can be differentiated using Src Mac Address. So, why do need DHCP client ID to differentiate the DHCP request. I understand that they need some IP address because ...
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3answers
813 views

Pinging computer on a local wireless network, what exactly happens?

I'm trying to get a better understanding of networking in general. Here's one of the many questions I got: What exactly happens (network wise) when I ping 192.168.0.5 from 192.168.0.3, when both are ...
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1answer
2k views

Can a VLAN have hosts with IP addresses outside it Subnet IP range scope?

I have 3 entities in my network. A server,switch and an appliance which acts as a DHCP/PXE server. When the server starts up, the DHCP server has to PXE boot the server. A seperate VLAN(1234) is ...
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2answers
226 views

DHCP client on Cisco 6509-E?

I'd like to have a Cisco 6509-E join a VLAN as a client so I can add some reachability SLAs across an organizational boundary. I've tried doing the usual "ip address dhcp" on an actual interface as ...
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1answer
68 views

Discovering public ip from wifi signals, shodan, parent router NAT [closed]

MAC addresses innately do not change right? and you're able to scan for broadcasting APs where you'll be able to detect different nearby mac addresses of each AP.. Public IP addresses change, ...
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2answers
779 views

Problem with DHCP for wired guest clients - Cisco WLC

I am very new to Cisco wireless. The most important settings on Cisco WLCs 5508 were done by external engineer. I have got an issue with wired guest network, my DHCP server (Cisco ASA Firewall) is not ...
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4answers
18k views

What is the difference between DHCP and NAT?

Both seem the same to me. I don't see how DHCP is different from Dynamic NAT. Can anyone please help?
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2answers
417 views

DHCP relay binding

As per my knowledge, the Relay agent does the job of forwarding the DHCPDISCOVER and DHCPREQUEST from the Client to the Server and DHCPOFFER and DHCPACK from the Server to the Client. But it not ...
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1answer
535 views

Use DHCP relay address as default gateway when no router option (3) included? [closed]

When I connect my custom embedded device to my network the DHCP responses do not include the router option (3). In this case should the device use the DHCP server ip address as the default gateway? My ...
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2answers
14k views

How are VPN Clients given IP addresses when they connect to VPN Routers such as VyOS? (How do Virtual IP Address Pools fit in?)

I'd like to know the nitty gritty details of how VPN Remote Clients are given Private IP Addresses on a Remote Network when they connect to the StrongSWAN or OpenVPN VPN Server that's embedded in VyOS ...
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1answer
588 views

GNS3 IP helper in Multiple Vlans

Good day everyone, I'am having trouble getting VPCs from VLAN 3 to communicate with the DHCP on Vlan 3 I've also tried configured IP helper on the Router but to no avail. Router Configuration dump ...
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1answer
8k views

Fortinet 200D: how to implement VLAN, inter-VLAN routing, and DHCP relay?

Here are the steps I configured so far: General configuration steps The following steps provide an overview of configuring and testing the hardware used in this example. For best results in ...
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1answer
168 views

Constant DHCP Requests with Cisco vWLC and Cisco 3560 setup [closed]

I'm having an issue identifying why my Cisco vWLC with DHCP bridging is flooding my DHCP servers with REQUESTS. These requests are coming in well over 1000/min. My Setup is in a lab, I am running a ...
2
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1answer
344 views

DHCP Relay Problem

I'm trying to get DHCP to work between these two Devices. Any tip's would be wonderful! Switch Config Switch#show run Building configuration... Current configuration : 1596 bytes ! ! Last ...
2
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1answer
1k views

How to setup a lease to 1 hour

I'm configuring a dhcp pool at my router (Cisco-7200) and I want to set the lease expiration to 1 hour. I checked the cisco manuals and I found this: lease {days [hours] [minutes] | infinite}. So I ...
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0answers
68 views

DHCP Requests not coming through [closed]

I've currently got a network issue that is preventing clients connecting to a guest WiFi network from getting an IP address via DHCP. I've been re-configuring and tweaking setting for the last few ...
2
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1answer
547 views

Cisco Router Logging DHCP Bindings to FTP Server [COULD NOT WRITE DATABASE HEADER]

Today I was working on my home lab for practice. I wanted to set my 2800 Series Cisco router to send a log of DHCP bindings to a FTP server on the local network (raspberry pi operating as sftp server,...
3
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1answer
84 views

DHCP server on HPE MSR2004 24G not working

I set up a new MSR2004 router and can't seem to get DHCP to work. Here are the corresponding config lines: dhcp enable vlan 12 name Guest Wifi VLAN dhcp server ip-pool guest-wifi gateway-...
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1answer
52 views

Initial connection to WI-FI

My question is what is happening during the initial connection to a wireless network , is there an Ethernet connection first and then DHCP or something else is happening before the device receive an ...
7
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1answer
796 views

Is possible to configure a Cisco 881 by DHCP?

I'm wondering if is possible to configure a Cisco Router 881 from a file on a tftp instruct on a DHCP option. I know is possible to configure the wan port through DHCP by configuring "ip address dhcp" ...
2
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2answers
510 views

Can't get DHCP to work in Spanning Tree

I'm not entirely sure what I'm doing wrong. I configured the inter-VLAN routing from the main router with the IP addresses I used as default router for the DHCP pools I also set in the main router. I ...
2
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1answer
770 views

MX80 Subscriber Management IP profile only active for stacked VLANs

I have configured subscriber management on an interface on my MX80 router. Both single and dual-stacked customers can be assigned (an) IP-address(es). For this I have created two dynamic VLAN ...
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1answer
10k views

How to configure VLANs with windows server 2016 DHCP in one VLAN [closed]

Here is an example of the network topology I am trying to create. There is the standard router - Netgear Genie. It can link each port to a VLAN, and the Wifi can be on the vlan, but my thought was to ...
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2answers
4k views

How Can I configure DHCPv6

I want to config one DHCPv6 server using Packet Tracer and with multiple routers, the router takes IP addresses from a server and distribute to computers .I have done that with IPv4 using IP helper ...
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2answers
5k views

Can not capture DHCP offer with wireshark?

I'd like to capture DHCP packets with wireshark. When I use the filter: "udp.port == 67 or udp.port == 68" I only see the Discover and Request broadcasts. While I thought the DHCP offer also gets ...
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2answers
2k views

What does ethernet switch do with IP address [closed]

Sorry about asking stupid question here but I'm very new to this field... Here is my current set up: _____ NAS | Modem --- Router --- Server |____ ...
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1answer
202 views

CanI prevent a secondary DHCP server on the LAN from taking over from SRX Juniper's DHCP?

I have admin access to a SRX550 Juniper, but I cannot get help from Juniper or joint their boards because the Juniper belongs to Century Link, not us. I have the following: # show system services ...
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3answers
3k views

Static IP's vs DHCP from management standpoint

I was recently graced with a new job opportunity in a large higher ed NE department. This is my first job working with a large network of several thousand users. Throughout my education, I followed ...
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1answer
1k views

Should DHCP relay and destination NAT work together?

Topology: [PC1]---lan----[RT1 / DHCP relay / DNAT]---wan---[DHCP server] [PC2]---------/ / [PC3]----------/ DHCP relay makes the a DHCP broadcast into a unicast and Forwards it to the DHCP server ...
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2answers
908 views

My tagged vs untagged configuration in my switch is not working as I expected.

My topology is pretty simple although dumb, I'm thinking in fixing it later. The goal: Pretty straightforward, Short Version: I want to create a VLAN for my guest wifi so people connecting to ...

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