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.
354
questions
0
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0answers
9 views
DHCP & DNS: Hostname Resolution [on hold]
Just making sure that I understand correctly,
When a new node on the network joins the LAN, it sends the DHCP server its hostname, and after the DHCP server acknowledges the requested hostname, the ...
0
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0answers
10 views
WatchGuard interface with secondary router holding WiFi splash page
I have a captive portal splash page I need to be presented to only 1 Open Wireless SSID on a WatchGuard AP controlled via the XTM330. The WatchGuard is not able to present the required splash page ...
0
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2answers
33 views
DHCP on CISCO 3850
I would like to configure the DHCP server on CISCO 3850, and reserve around 100 static IP for servers
After doing research found that I need to create individual pool for each static maping like ...
0
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0answers
22 views
DHCP assigns wrong IP [closed]
i recently changed my rourer with a new one and set it up with exactly the same configuration but when i try to connect via WIFI my phone gets an IP that is like this 192.168.1.xxx when the DHCP is ...
0
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1answer
46 views
ARP after DHCP discover
Hey All,
I was working on DHCP lab
As seen in the below figure when I take a pcap between e2 and R1 [in a situation where i shutdown the f0/0 interface on R1 and startup again] I see an ARP ...
0
votes
1answer
35 views
What's the difference between DHCP Disabled or Relay on an access point?
I am trying to turn my old router to an access point for the new router, I assigned an IP address in the range of the new one and when I went to disable DHCP there was another option which is Relay ...
0
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0answers
23 views
How to implement port security in SDN using pox controller and ovs?
How can I defend against DHCP starvation attacks or MAC spoofing in an SDN environment?
5
votes
2answers
88 views
Interface VLAN IP address not on exclude list?
Does an IP address need to be included in a ip dhcp excluded-address x.x.x.x if its already included in an interface vlan?
Examples:
ip dhcp excluded-address 10.3.8.1 10.3.8.20
interface Vlan30
...
3
votes
1answer
43 views
pfsense DHCP lease remember time settings?
pfSense remembers DHCP leases for a quite long time, which is good use on a LAN where the same machines request IP numbers frequently and have a chance to always get the same leases. However on an ...
1
vote
2answers
46 views
How to give one pc with dhcp a default-gateway while the rest use static ip and static default-gateway
I have this topology where the PC0, Server0 and PC4 use static ip and static default-gateway, but one pc is Request DHCP, so i have to use DHCP ip address for him and static ip for the rest, now the ...
2
votes
1answer
65 views
How to prevent manual assignment of an IP of VLAN/subnet A when connected to a VLAN/subnet B?
I'm configuring a Cisco router C1111-8p using IOS XE 16.8 with 3 VLANs.
VLAN 1: native/management 192.168.0.0/24
VLAN 10 : 192.168.10.0/24
VLAN 20 : 192.168.20.0/24
I haven't set ACLs up yet but ...
2
votes
1answer
19 views
Shoretel ST1D Switch not accepting assigned IP
After configuring a Shortel ST1D switch, I connected the LAN1 Port from Shoretel ST1D to my Cisco 4507R switch. I attempted to ping the IP that I set specifically on the ST1D switch and I wasn't able ...
3
votes
2answers
135 views
How does a DHCP relay router forward the packet to the server?
We know that routers do not forward broadcast messages. So when a DHCP relay router receives a DHCP Discover message, the destination IP address is going to be 255.255.255.255 because at this stage ...
1
vote
2answers
176 views
Cisco DHCP Router
I have come across an issue and I’m not sure on how to resolve. I’m trying to get the router to assign the PC’s within my network IP addresses. I have excluded the ones which i wish to not be used ...
1
vote
1answer
25 views
How do devices with static IP behave themselves when plugged to a new network? [closed]
I'm trying to understand how to determine if a device plugged to my PC with Ethernet cable has a static IP.
What I'm trying to do is to sniff DHCP packets that it sends and by looking at DHCPDISCOVER ...
1
vote
2answers
52 views
What happens when DHCP client and server are on different VLANs [closed]
I'm trying to create a lab on PT and I've attached an image. But for some reason my PC is not able to get an IP address from the DHCP server. There is no issues with layer 1 and layer 2. I checked ...
1
vote
0answers
69 views
Customized captive portal with external DHCP server [closed]
I am stuck in one issue for which I need your help on this. Actually its bit complex to explan about my situatuion but I will try my best.
I am working on customized captive portal on arm processor ...
2
votes
2answers
60 views
Client timeout for Cisco IOS Static DHCP Pool
I'm not a network admin, but I have an old Cisco Catalyst 3560 for my network. I've successfully set up a DHCP Pool:
ip dhcp pool 192.168.0.0
network 192.168.0.0 255.255.255.0
default-router 192....
0
votes
1answer
65 views
Configuring HP Smart Switch and SonicWall with VLAN
I'm trying to configure an HP SmartSwitch with a Dell SonicWall on a VLAN for some computers in our network.
The computers in question are on port 37 on the switch. I've created a new VLAN interface ...
0
votes
0answers
14 views
DHCP Layer 2 and Layer 3 [duplicate]
I am having a difficult time to visualize the conceptions of DHCP Discover message in order to receive an IP address sends out a broadcast at both layer 2 and layer 3.
Can someone care to explain?
...
1
vote
1answer
121 views
No DHCPOFFER message captured in Wireshark
I am looking for the answer why packet captures in Wireshark doesn't contain DHCP offer message. I was trying to capture packets directly on the computer with installed Wireshark and doing a SPAN ...
1
vote
0answers
36 views
Cisco ASA: Windows DHCP doesn't bind IP address after failover change active [closed]
Equipment and soft:
Two Cisco ASA 5540, ASA ver. 9.1(7)32, active/standby failover
DHCP server: Windows server 2016
Anyconnect VPN clients get IP addresses from DHCP servers. Everything works ...
1
vote
0answers
39 views
DHCP over Frame Relay [closed]
I have two co-operate buildings. Building A is connected to building B via frame relay. Building A has the main switch server (with VLAN info) and a DHCP server. I need Building B devices to receive ...
0
votes
1answer
101 views
Is there such a thing as a “fallback” DHCP server? [closed]
Suppose I have a network 10.0.0.0/24, and a DHCP server that allocates addresses under that network.
My question is simple — I have a separate box which is also capable of acting as a DHCP server. ...
3
votes
1answer
81 views
Host IP address vs gateway IP address vs DHCP IP address
What is the difference between a host IP address, a gateway IP address, and a DHCP IP address when setting up networking devices?
For example, when configuring a virtual network adapter for my VM, I ...
0
votes
0answers
54 views
Cisco ASA L2TP remote-access VPN with addresses assigned by DHCP
I have an ASA with a working Cisco VPN Client configuration set up. I am trying to phase out the Cisco VPN Client, initially in favour of L2TP.
The Cisco Client policy has end-users fetch their ...
1
vote
1answer
37 views
Cisco 887VA not handing out IPs to new requests
A few days ago seemingly with no changes (other than we changed the adsl mode on the controller). DHCP has stopped working for 2 of the 3 vlans we have configured on a Cisco 887VA.
From the Cisco ...
3
votes
1answer
46 views
ip dhcp class command
Here is a DHCP configuration that we have here:
ip dhcp class range
ip dhcp pool abc
network 10.10.10.0 255.255.255.0
default-router ...
class range
address range 10.10.10.10 10.10.10.254
My ...
1
vote
2answers
85 views
Get DHCP IP with subinterface
Router0 has 1 subinterface on gi0/0 and can't get a ip trough dhcp. Is there something I forgot?
The configs:
Router0(got no ip from dhcp):
interface GigabitEthernet0/0
ip address dhcp
duplex ...
1
vote
1answer
43 views
Dhcp Broadcast Through Switches
Think of a pc connected to switch1. Sw1 is connected to sw2(trunk port on both switches) and sw2 is connected to a router(dhcp server). Pc sends a dhcp broadcast. Does sw1 passes the broadcast through ...
1
vote
1answer
41 views
DHCP Broadcast on SVI
Think of a dhcp broadcast going through multiple switches. What happens to that broadcast when it reaches the vlan interface (svi)?
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votes
2answers
57 views
How can TCP be used in order to implement DHCP and under which circumstances is this preferable?
I am pretty new to the computer networking studies and was learning about the DHCP protocol. It is implemented based on UDP, as I've gathered, but is there a way for it to be implemented over TCP? ...
1
vote
1answer
44 views
Why aren't we using digital signatures for the DHCP?
Why aren't we using digital signatures for the DHCP in order to stop Rouge DHCP attacks?
0
votes
1answer
24 views
faild hardware address for ifd ge-0/0/0 failed on junos-vsrx-12.1X47-D20.7-domestic vmware machine
I have been trying to configure dhcp client on ge-0/0/0, I have asked a question before about it in this link
At first the solution provided worked, but when I started the virtual machine again it ...
0
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0answers
18 views
DHCP Broadcast messages [duplicate]
Why are there so many DHCP broadcast messages while trying to give a computer some network settings?
2.Last,when can these broadcasts be avoided and how are DHCP relay agents related to the whole ...
0
votes
2answers
215 views
Importance of DHCP option 12, client host name
The main purpose of a DHCP server is to provide dynamic configuration for a group of hosts (mainly IP, Gateway and DNS). There are several options that can also be sent.
Option 12 (client hostname), ...
3
votes
1answer
157 views
Configuring DHCP on Juniper junos-vsrx-12.1X47-D20.7-domestic on vmware
I'm preparing for JNCIS-SEC exam. I used junos-vsrx-12.1X47-D20.7-domestic image to create virtual machine in order to practice for the exam.
I am following this to configure the vsrx. When I do the ...
0
votes
1answer
36 views
Connectivity from DHCP-based machines to servers with static IP addresses on the same gateway
I have Comcast service with 5 static IP addresses, using a Cisco DPC3939B as the cable modem. In addition to the 5 machines with static IP addresses, there are additional devices that get their IP ...
1
vote
1answer
47 views
Can a machine be its own DHCP server for another interface?
I was wondering if a single machine (with several network interfaces) can be, at the same time, a DHCP server and a DHCP client, that is the server would dynamically attribute an IP address to an ...
1
vote
1answer
78 views
Why do Cisco IOS switches send packets to DHCP servers with zero giaddr field when DHCP snooping is on?
I recently troubleshooted a network where the switch had DHCP snooping turned on and even though the router which was acting as a DHCP server was connected to a trusted port, the client wasn't able to ...
2
votes
3answers
87 views
Sonicwall DHCP client option code
Is it possible to set DHCP option codes for the DHCP client (the WAN interface)?
I am quite sure that you can send options in a DHCP request, I quote: "This option is used by DHCP clients to specify ...
0
votes
2answers
62 views
Sonicwall DHCP Reserved IPs Broken After Expanding Subnet
I've just expanded our subnet at work from /24 to /22 now that we've started running out of IPs. For ease of transition, I left all statically-assigned IPs at their original addresses and moved the ...
2
votes
0answers
51 views
DHCP ivp6 vs DHCP ipv4 router config (cisco)
When setting up a router as dchp server in ipv4, we specify a pool under which we give the network and the default-gateway and that's it:
However in ipv6 stateless dhcp , we create the pool then ...
3
votes
3answers
525 views
Basic networking and DHCP theory
Background
We're organizing an event where we need to connect about 10 PCs into a single LAN network (no internet access). We've got some general experience with "home" and "web" networking but we've ...
3
votes
1answer
224 views
DHCP OFFER not reaching client through several routers and ASA [closed]
So recently we received notification from one of our remote branches that certain PCs were unable to connect to the internet. We determined that DHCP was the cause. The basic L3 path between the ...
1
vote
1answer
123 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 ...
1
vote
0answers
117 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 ...
1
vote
1answer
187 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 ...
1
vote
1answer
1k 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?...
2
votes
1answer
2k 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 ...
