Hi All,

I have been trying to install my DHCP server. I am seeing this error message after I typed:

systemctl status -l dhcpd

active: failed

The error messages followed after that. And I get this "bad subnet number/mask combination" error message.

My IP is 192.168.1.138 and netmask is 255.255.255.0 (I acquired these addresses after I typed ifconfig).
Then I set my network setting to these addresses.

And the error says there is an indication that the last "0" is the bad choice. I have also tried /30, and still didn't work.

And now this system is not even connected to the internet (server not found), although the connection is good. Nothing wrong with router, or the modem.
But if I typed 192.168.1.138, my Apache server is up.

What else can I try?

By the way, I am using CentOS7.

#Basic subnet declaration#
subnet 192.168.1.138 netmask 255.255.255.0 {
range 192.168.1.150 192.168.1.160;
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
}


Thank you all for your help,
Denny

We would need to know more to understand your issue. But...
mask 255.255.255.0 would match the format /24 not /30.

What is at 192.168.1.138? Is that your DHCP server address, or your workstation node (dhcp client) address?
Is that also your router and so your default gateway, or is that another node?
WHERE are you seeing this error message, at the server, the client, or elsewhere? And under what conditions or in what file?

1 members found this post helpful.

Could you provide more information about the what you have done? The exact text of the relevant portions of configuration files would likely be most helpful; be sure to surround them with "code" tags, which become available when you click the "Go Advanced" button beneath the "compose post" window.

This article should help: https://www.centos.org/docs/5/html/D...ng-server.html

In addition, you may wish to read this: https://www.linuxquestions.org/linux...Ask_a_Question The more information you provide, the easier it is for others to help you.

Oh, and welcome to LQ.

Hello....

192.168.1.138 is the IP address for this DHCP server AND the for the network setting. My dhcp client is on another machine.

This DHCP server is connected to a router.

I am seeing this message after I typed:

systemctl status -l dhcpd

active: failed

and the error messages followed after that.

Thanks again,
Denny

I am not sure what you are trying to say here. You might need to provide more information on your network configuration but the subnet should be

1 members found this post helpful.

Well, 192.168.1.138 is not within the range 192.168.1.150-160.

1 members found this post helpful.

Hi,

Can I have the range 192.168.1.136 192.168.1.160;
?

Thanks again,
Denny

The range can be anything within 192.168.1.1 - 1.192.168.254 but it can not include the router and the IP address of the DHCP server itself. You can also have multiple ranges. The DHCP server does have a static IP address?