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

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6 views

DHCP Troubleshooting Win 2008 Server [on hold]

I can see with WireShark that a client is making a DHCP Request but it does NOT respond with the ACK. How can I troubleshoot this? The client is a Netgear Switch.
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0answers
9 views

Firewalls / port-forwarding within simple home network? [on hold]

I have a router running dd-wrt. I have two laptops that got their IPs via DHCP in the usual 192.168.1.0/24 , no IP collisions or anything strange there, using the wireless routing on the router. ...
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0answers
11 views

DHCP overloaded on home network? [on hold]

I've recently switched a bunch of our wireless devices (Sonos speakers, Chromecasts, etc.) to use wired LAN. I've got a low-to-mid-range TP-Link router (with Gargoyle) with standard DHCP settings that ...
-2
votes
1answer
21 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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0answers
55 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 ...
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1answer
33 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 ...
2
votes
1answer
116 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
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1answer
52 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
35 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
66 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
40 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
28 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
54 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
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2answers
66 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
60 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
80 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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1answer
26 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
51 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
109 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
156 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
77 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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0answers
47 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
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1answer
82 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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1answer
81 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
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1answer
69 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 ...
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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
47 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
108 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
36 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
74 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 ...
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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
47 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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2answers
282 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
54 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 ...
1
vote
1answer
118 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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0answers
17 views

Should static IPs be set on the DNS/DHCP server, the host, or both? [closed]

Assuming a pretty regular business setup, when assigning static IPs for servers to use, should they be assigned on the DNS/DHCP server? Should they be configured individually on the hosts? Or should ...
1
vote
1answer
70 views

Constant DHCP Requests with Cisco vWLC and Cisco 3560 setup

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 ...
16
votes
3answers
1k views

Why is broadcast used at the DHCPREQUEST step?

This is the process of DHCP operation, My question is at the 3rd step why does the Client send a Broadcast and not a Unicast as after the previous two operations the address of the DHCP server / ...
5
votes
2answers
4k views

dhcpv6 - stateful VS stateless, what is difference between it?

Can someone explain me, what is difference between DHCPv6 Stateful and Stateless? I was looking on the net and, surprisingly, I found only the remains of information but some general comparison or ...
1
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1answer
266 views

How to set up DHCP in tagged VLAN with Cisco 300 switch

I have been searching for a while but not yet found the correct answer. First, I am pretty green with networking, so I will try to explain as precise as possible. I am tasked with setting up a dhcp ...
0
votes
1answer
42 views

Configuring DHCP server [closed]

I am playing around in my virtual environment and I would like to find out what is the best practise to configure DHCP server - configure it on the Router or Server running Windows Server or some type ...
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0answers
212 views

Erratic behaviour on ISR 4331 dhcp client

I'm new to this kind of networking equipment so I ask you to be patient and kindly bear with me. Also, I'm not connected to that router right now, so I can't copy-paste the exact responses I get. I ...
1
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2answers
1k 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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2answers
299 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 ...
1
vote
1answer
106 views

Can not receive DHCP request from different VLAN

I've been faced with this. I've set up a DHCP pool at the server with the following configuration: pool-vlan20 default gateway: 192.168.2.1 start ip: 192.168.2.100 The router has been set up as the ...
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2answers
682 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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1answer
43 views

Why is my Cisco MMS891 assigning IP addresses with static NAT entries to devices via DHCP?

I have a Cisco MMS891 ISR as my edge router with several static NAT entries, which are set up to NAT my LAN IP addresses (which are statically assigned to printers) to access an externally hosted ...
0
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1answer
120 views

Is this a valid network diagram?

I'm studing how to create a network diagram to this problem The problem is: 7 condominiums with 7 floors each one, each floor has 4 apartments The project is needed to use VLANs, Routers, DHCP, DNS'...
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1answer
739 views

ACL for DHCP configured on Cisco switch

We have a DHCP pool configured on Cisco L3 switch for hosts on SVI. Since we want to restrict connectivity to DHCP which is on the same switch. excluded 172.24.19.1-172.24.19.50 SVI IP 172.24.19.50 ...
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1answer
379 views

Cisco IOS pick default route from two DHCP interfaces with track

I plan to have a portable IOS cisco router which will have two DHCP assigned ISP addresses from unknown ranges. A tunnel is then built through the preferred ISP to another outer. I would like to set ...