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.
427
questions
0
votes
0answers
5 views
the tracert command with VPN [closed]
When using VPN, the tracert command to a website doesn't print the private IP address of my router. Why?
I thought the route would be like this:
my router -> the ISP contacting with me -> others ...
0
votes
0answers
16 views
Configure DHCP for VLAN [closed]
I'm configuring DHCP for VLAN on a router. At last, the computer can not retrieve the IP address.
Below is how I have configured.
Switch
Switch>en
Switch#conf t
Switch(config)#vlan 10
Switch(...
0
votes
2answers
51 views
How does DHCP work?
I'm carrying out an experiment to test the mechanism behind DHCP.
In this topology, I disable the link between the switch and the router. However, the computer still request IP address successfully.
...
0
votes
0answers
16 views
List DHCP pool in an interface [closed]
I have assigned 2 dhcp pool for an interface. When a computer request for an IP address, which pool will be chosen? What is the command to list all dhcp pool?
0
votes
0answers
9 views
ISC-DHCP-server on ubuntu not working [closed]
Im trying to get a dhcp server running on my Ubuntu 20.04 laptop. the PC will most of the time not be connected to internet as it will be in the bushlands.
I have tried to install the isc-dhcp server ...
0
votes
0answers
12 views
Static IP address and DHCP [closed]
Hellow,
If I gave to device a static IP address (for example, Raspberry PI),
But I didn't reserve it in the DHCP.
The DHCP can "offer/give" that IP to other devices?
** The Raspberry PI is ...
2
votes
1answer
58 views
How does a DHCP server know which network interface and subnet the new IP address should be on
I've read that DHCP servers add a column to your iptable in your router. A new dynamically created IP address with a network interface and a subnet mask. Then the IP address is matched with your MAC ...
0
votes
1answer
31 views
How can u assign IP addressing for point to multipoint switches that connect to only one router?
I was wondering if I can assign two network address in a LAN while the switches are point to multipoint which connect to only one router.
How will me DHCP going?
Router - Switch 1 - Switch 2,3,4
3
votes
1answer
47 views
how to configure dnsmasq client-identifier for juniper prefix host-name
I have a Juniper switch that has a dhcp-client configured like this:
show interfaces irb unit 0 family inet dhcp
client-identifier {
prefix {
host-name;
}
}
I ...
-1
votes
1answer
40 views
Apply Interface Default Gateway to Entire Device
I feel there may be a very simple term for what I trying to do, but I'm not sure what it is, and it is difficult to search for it in concise words.
The shortest description I can come up with: "I ...
0
votes
1answer
57 views
Configuration of DHCP for multiple vlans
I have the following network on Packet Tracer. The hosts are in different vlans each one. My goal is that the DHCP server can give IP to the hosts.
Here is what I made for each vlan (the example is ...
0
votes
1answer
38 views
Do IPv6 addresses have better persistence with DHCPv6?
I have a LAN with about 25 devices that occasionally grab each other's IP address via DHCPv4. I know there are certain lease time limits and it can be set to very long periods to work it around to an ...
3
votes
2answers
53 views
IRDP protocol nowadays
I'm considering to remove rdisc tool from iputils project (see https://github.com/iputils/iputils/issues/363). This tool implements ICMP Internet Router Discovery Protocol (IRDP).
Is IRDP really ...
0
votes
1answer
83 views
Configure dhcp relay agent and router on stick
I need help. I don't know what i did wrong because i have configured the dhcp pool, subinterfaces and dhcp relay agent. Gateway pc uses static ip address while Branch pc acquired their ip address ...
0
votes
1answer
22 views
Assigning static IPs to VoIP phones in packet tracer
Is there a way to assign IPs and dn to VoIP phones in a network configuration without using DHCP?
Such that if I have PCs and VoIP phones connected to the same switch, which is connected to a router ...
2
votes
4answers
234 views
How to add two VLANs for DHCP Pool
Currently one of my customer has DHCP pool created in Cisco Switch and ip address range is 192.168.25.0/24 (This is a VLAN). Now they have 230 devices and They are going to increase device count by ...
2
votes
1answer
32 views
Assigning static IP address from the DHCP pool range on Cisco 800 series
What happens if I assign a static IP address to a device in a LAN where there is an active DHCP server and the address falls within the configured DHCP pool and DHCP server is Cisco 800 Series?
Most ...
0
votes
0answers
38 views
Cisco DHCP using dynamic updates
I would like to use a configuration on a Cisco router that allows for clients to resolve the names of other clients without the use of mDNS. I have following configuration:
roTST01#show running-config ...
0
votes
1answer
124 views
Cisco IOS - Delay DHCP offers
I have two routers in the same subnet that have a HSRP configuration in order to take over, if one of the device fails. There is the same DHCP configuration on both devices:
ip dhcp pool LAN
network ...
2
votes
0answers
122 views
Communication between subnets on Sonicwall firewall
I have a Sonicwall TZ-350. X0 is the default LAN with IP 192.168.10.1, and X1 is the WAN. I've set up a second local subnet on X2 with IP 192.168.20.1 for a single NAS device (no switch; the device is ...
0
votes
1answer
47 views
DHCP Packet Drops on Return
The DHCP packet makes it from the Security computer all the way to the DHCP server and back to Router1 but gets stuck there. All all packets make it across when the device has a static ip assigned.
...
2
votes
1answer
49 views
Does an IPv4 DHCP Relay Agent care about Option 80 (rapid-commit)
I'm trying to figure out if an IPv4 DHCP Relay Agent needs to care about a rapid-commit (Option 80) included in a DHCP Discover.
My understanding is that the Relay Agent is supposed to simply converts ...
1
vote
1answer
72 views
How does a device receive default gateway IP address?
When and how does a device get information about default gateway in LAN? I know you can define default gateway statically, but which protocol is used when it is not statically defined? Is it from ...
1
vote
1answer
85 views
DHCP Help 3560-CX + Aruba AP515
The problem
VLAN 100 is not assigning IP address to the SSID Guest from the AP, but Aruba is Tagging the SSID to be VLAN 100. How do I get the Switch to assign the DHCP? On the switch, it seems to ...
0
votes
0answers
16 views
Arp Access-List Without An Interface [duplicate]
I have dhcp snooping an arp inspection setup on my VLAN. I have a number of clients that need to be statically set on this VLAN but still plug into a DHCP access port on the VLAN. I have ip dhcp ...
0
votes
2answers
82 views
IP Snooping\ARP Inspection With Static Devices On DHCP VLAN
Consider this network:
I have enabled DHCP snooping on my system. Switch A has the DHCP connected and the port on VLAN 70 for DHCP has been trusted to allow for reading the database and passing ...
0
votes
0answers
48 views
Cisco FTD DHCP option codes
I have a Cisco ASA 5515-X that is currently running ASA with the FirePOWER module, which cannot sent option code 60 in the DHCP request. My ISP requires me to send this.
Does anyone have FTD 6.4 (or ...
0
votes
0answers
24 views
DHCP helper flow in incorrect config
Discovered a configuration error in our network and would like to double check if the conclusions I drew from it are correct.
Incorrect configuration:
dhcp helper set on VLAN xyz to point at DHCP01 ...
1
vote
1answer
96 views
How does Network Layer behave when client received a unicast DHCP offer?
I went through various stack exchange post to understand the concept of DHCP offer when it comes as a unicast to client from the DHCP server.
A server can send a unicast DHCP offer since it knows the ...
1
vote
1answer
54 views
Is it possible to configure DHCP on a router or UTM firewall for the multiple VLANs on L3 Switch?
I'm working on expanding our office network to accommodate more users/devices. Currently we have the DHCP configured on a UTM firewall(cyberoam ing50) device(cum router) providing IP addresses for ...
1
vote
0answers
40 views
1941W wireless clients losing DHCP IP address [closed]
I am attempting to 'extend' a 192.168.1.0\24 network with an experimental network 192.168.10.0\24 using a 1941W router.
I have configured 1941W to distribute a 192.168.10.0\24 network, with WLAN ...
0
votes
0answers
34 views
Next-server option missing in dhcp server on EXOS switch
I'm trying to utilize the build-in DHCP server on our EXOS switch.
Address pools work as intended. So far so good. But I also need to boot our FOG iPXE server through it. The configuration of the ...
0
votes
1answer
235 views
Cisco IOS Software [Everest], ISR 4331. Vlan+Vrf+Dhcp
I'm looking after to use a setup with that objectives in mind:
Create a subinterface on interface GigabitEthernet0/0/1
create a Vlan and assign it to that subinterface
create a vrrf and assign it to ...
0
votes
1answer
141 views
Cisco ip helper-address
I am looking at the DHCP documentation and i cannot seam to find how to configure the router to use a loopback interface as the relay-agent. My objective is to use option 82 so that the dhcp server is ...
0
votes
2answers
130 views
Per-VLAN DHCP pools on the switch
Let us say I have a switch on which I have created two VLANs 10 and 20. I have set ports 1-10 to be on VLAN 10 and ports 11-20 to be on VLAN 20. Presently the PCs in both VLANs are configured with ...
2
votes
2answers
654 views
General: What is a dynamic gateway, how does it work, where is it used?
I saw this option in my OPNsense gateway configuration, and was hoping someone could shed light on what it is, exactly:
Dynamic gateway policy: [YES/NO]
This interface does not require an ...
0
votes
1answer
41 views
Are new DHCP options sent automatically to clients?
When new DHCP options are configured on a DHCP server (Like NTP and DNS server options) are these sent out to clients automatically?
if clients were provided an infinite lease time and so they would ...
0
votes
4answers
752 views
How the device chooses between multiple DHCP pools?
In a router , you can create and configure multiple DHCP pools each one with its own default route and dns server . And because the DHCP pool configuration is not specific to an interface in a router, ...
0
votes
2answers
48 views
Cisco 2960-CX - Dynamic Management IP over trunk link
I have a Cisco 2960-CX switch mounted in a Mobile CT (hospital owned). This "trailer" moves between my 7 campuses as needed. Is there a way for the switch to obtain an IP address ...
0
votes
1answer
41 views
Question about the rebooting state of the DHCP protocol [closed]
Taking into account this diagram...
I wonder if a device, after a reboot having a previous known configuration, uses it from the start even tho it's still asking to check if it can continue using ...
0
votes
3answers
6k views
how to capture DHCP packets in wireshark
Hy!
I want to capture DHCP packets in Wireshark but I did not receive any. Not my filter wrong, I don't get any. So I think I can't trigger the DHCP communications.
my filters:
dhcp
bootp
udp.port == ...
1
vote
1answer
86 views
Will devices with static addresses, will be disconnected when DHCP Server is changed?
In my office network, the DCHP Server is set to 192.168.0.1/24.
I want to increase the available pool, so I am thinking update the above setting to 192.168.0.1/23 in order to have:
Network: 192.168....
0
votes
1answer
203 views
Best practice / advice for cisco 3560 behind Virtualised OPNsense
Currently I run the below scheme. The problem is that when ESXi is down it takes down all the network with it, so I have to boot up another router to log in to it.
WAN > OPNsense (in ESXi)> ...
0
votes
1answer
526 views
Some mobile clients are unable to connect to UniFi AP mysteriously
We have two UniFi Controllers, one contains the main internet its directly connected to the fibre and then we give internet to the second controller using LAN connection, internet works fine in main ...
0
votes
1answer
58 views
Juniper / SRX-100 / Repurpose old device / Disable DHCP?
I have an old Juniper SRX-100. I want to re-purpose it for my network. I need to extend the network in a new location, so I need more ports. I could use a simple switch, but I have this laying ...
0
votes
2answers
69 views
Why we define pool for declaring CISCO router DHCP?
In case declaring DHCP server in CISCO routers, should define pool with network addresses.↓
Example
Router(config)#ip dhcp pool net1
Router(dhcp-config)#network 192.168.1.0 255.255.255.0
The router ...
2
votes
2answers
172 views
Security issues with DHCP snooping on cascading switches
Consider the following topology:
This image was copied from here and in this article it specifies the following:
Remember that port Fa0/24 on SW2 is an untrusted port from DHCP Snooping’s point of ...
0
votes
4answers
292 views
Assigning IP addresses to multiple switches
Thank you in advance for taking the time to read my question, i appreciate it. I am in need of help on IP assigning to 4 brand NEW Araknis switches that I am replacing with the current netgear/tp-link ...
2
votes
1answer
111 views
Why can my device not get an ip from DHCP in a network with 2 VLANS of which one has DHCP?
In our company we have a CISCO 2811 Switch accompanied by an HP1920 Switch. Our current configuration consists of 2 VLANS:
VLAN-2 that has no DHCP in IP range 192.168.0.0/24
VLAN-5 That contains DHCP ...
0
votes
0answers
82 views
Why DHCP client doesn't issue a DHCPREQUEST as it has received a DHCPOFFER?
In GNS3 (and using Cisco routers), I've created four subnetworks like the following:
The goal is to set up a DHCP server on router R1 and a DHCP relay agent on router R2 in order to make it available ...
