Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Dynamic Host Control Protocol - automatic assignment of addresses to network devices. Questions about configuring it, blocking rogue DHCP servers, etc.

0
votes
0answers
15 views

how to cinfigure Client Link-Layer Address Option in wide-dhcp6s?

i try to undersstand how to configure Client Link-Layer Address Option https://tools.ietf.org/html/rfc6939 in wide-dhcp6s dhcpv6 server , it sodumenation are https://www.systutorials.com/docs/linux/...
0
votes
1answer
61 views

How VLAN devices will get automatically IP from DHCP server

I have one Windows server 2012R2 which has 10.219.1.1 IP address & I also have Cisco Catalyst 2960-X Series which is layer 2, we managed to do inter VLAN routing by updating its firmware, where we ...
0
votes
0answers
36 views

Guest Vlan has internet, but no DHCP

We have our main VLAN working on a HP Procurve 2920 switch, on a class c subnet (10.10.61.0/24). I setup a guest VLAN for the guest WIFI that is on a class c subnet (172.16.254.0/24) also. Created a ...
1
vote
0answers
23 views

Is a dedicated DHCP server required for PXE boot? [closed]

Read a lot of posts on PXE server setup. Most of them mention to setup DHCP server. My question is even though we used a managed switch (e.g. Cisco SG-300), which comes with DHCP functionality, do we ...
0
votes
1answer
33 views

Two ip helper for two different services?

There is a vlan5 currently configured with an ip helper-address to forward the broadcast traffic to our DHCP on a different vlan. Works perfectly and everyone is happy. interface Vlan5 description ...
0
votes
1answer
43 views

Single DHCP server for multiple VLANs (packet tracer)

I have a layer 2 switch, PC 1 connected to port 1 and PC 2 connected to port 2. Port 1 is in VLAN 20 Port 2 is in VLAN 21 Can I use a single DHCP server without a router and give IP to both the PCs?...
1
vote
1answer
33 views

How to configure DHCP pools for 2 VLANs/subnets sharing a switch

I've set up DHCP pools on a layer 3 switch that goes out to 13 layer 2 switches. Most of which have their own subnet and VLANs, and everything works fine when that's the case. But when there are two ...
0
votes
2answers
32 views

Is it possible to enable DHCP on multiple hosts via Cisco switches or routers? [closed]

I think I know the answer to this, but thought I ought to ask around. When setting up new networks with multiple hosts, like a university computer lab VLAN with 30+ workstations, for instance, is it ...
0
votes
2answers
48 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 ...
2
votes
1answer
70 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 ...
0
votes
1answer
64 views

Vlan cannot get DHCP address from using Router and L3 Switch

Simplified diagram of a larger network, but I'm having trouble getting DHCP from the router. Going into simulation mode in packet tracer, I'm seeing an error on the layer 3 switch saying "There is no ...
0
votes
1answer
45 views

DHCP relay on Juniper MX

Hi I got a problem with bootp relay on a juniper router(s). I got helpers bootp interface configured with: irb.10 broadcast server 10.20.1.10 server 10.20.1.11 theres several irb ...
0
votes
1answer
25 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 ...
2
votes
4answers
160 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 ...
0
votes
1answer
32 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 ...
0
votes
0answers
14 views

Multiple DHCP in SonicWall

can someone please tell me if its possible to create a separate Zone (lets say for port X3) of course using a different subnet than X0 with its own DHCP? I don't need traffic between X0 and X3, ...
1
vote
1answer
63 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 ...
2
votes
1answer
50 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 ...
1
vote
1answer
60 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-...
-2
votes
1answer
23 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 ...
0
votes
1answer
75 views

Cisco 2960 not receiving dhcp from the router

I have a problem with Dhcp of some the Vlans. here is how my network is : I have a router ASR1001, which connects 15 switches(2960) as a ring topology. each switch has a subinterface of the router ...
1
vote
1answer
54 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 ...
3
votes
1answer
207 views

Why are DHCP ACK and REQ messages broadcast in Link Layer?

When I look at the protocol, I see that DHCP Request and Acknowledgement are both broadcast in the link layer. However at that point, both sides actually know each other's MAC addresses. Why do they ...
0
votes
1answer
401 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 ...
0
votes
2answers
36 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 ...
1
vote
2answers
117 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]---[...
1
vote
2answers
58 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 ...
1
vote
1answer
49 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 ...
0
votes
2answers
70 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, ...
0
votes
2answers
147 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 ...
1
vote
3answers
64 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 ...
0
votes
1answer
192 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 ...
0
votes
1answer
27 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, ...
1
vote
2answers
55 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 ...
0
votes
1answer
298 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 ...
-6
votes
4answers
767 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?
0
votes
2answers
118 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 ...
0
votes
0answers
51 views

Dhcp server not working after server bootup when plugged into managed switch

I have very simple network with one DHCP pool. I've installed ISC dhcp on ubuntu linux and everything works fine and fast on simple unmanaged switch. After connect server to managed switch TP-Link ...
0
votes
1answer
200 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 ...
1
vote
1answer
128 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 ...
2
votes
1answer
77 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 ...
1
vote
0answers
53 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 ...
3
votes
1answer
52 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-...
2
votes
1answer
167 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,...
1
vote
1answer
37 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 ...
1
vote
1answer
81 views

Set up 2 VLANs and rate limit Internet bandwith

I generally work with software instead of networking so please bear with me. I have a good understanding of simple network principles like subnetting, DHCP, DNS and the like but have a slightly more ...
0
votes
2answers
65 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 |____ ...
1
vote
1answer
57 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 ...
0
votes
2answers
608 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 ...
0
votes
2answers
69 views

Will DHCP server know about the statically allocated IP addresses for any of the device under its purview? [closed]

For simplicity sake, let us say, the DHCP server is running in the default gateway/router at 192.168.1.1/24 And let us say, i have connected 10 hosts to the router. And among 10 hosts, 2 of the ...