How to clear NIC cache?

n00b_noob · 09-10-2020, 02:30 PM

Hello,
I'm using CentOS 8. when I set a manual IP to my NIC and back it to DHCP then the NIC IP doesn't change. I restarted "networking" service and used "ifdown" and "ifup" commands too, but problem exist.
How can I clear NIC cache or Flush it?

Thank you.

scasey · 09-10-2020, 04:29 PM

Is the manual IP in the range of dynamic addresses provided by the dhcp server? If so, changing the type from static to dynamic may not cause the IP address to change.
There isn’t a “NIC cache” afaik

n00b_noob · 09-11-2020, 04:03 AM

Quote:

Originally Posted by scasey

Is the manual IP in the range of dynamic addresses provided by the dhcp server? If so, changing the type from static to dynamic may not cause the IP address to change.
There isn’t a “NIC cache” afaik

Yes, it is.
As I said, after changed the IP address, I restarted networking service and I used "ifdown" and "ifup" to bring NIC Down and UP.

michaelk · 09-11-2020, 09:16 AM

As a frame of reference it worked for me.

How did you set a manual IP address? Did you manually edit the ifcfg configuration file or use the Network Manager applet?

If you manually edited the ifcfg file then without seeing those changes it is difficult to determine what is not working. ifdown and ifup actually use Network Manager's cli interface i.e. nmcli to stop/start networking.

If you installed the legacy network-scripts package make sure you stop network manager.

scasey · 09-11-2020, 02:17 PM

Quote:

Originally Posted by n00b_noob

Yes, it is.
As I said, after changed the IP address, I restarted networking service and I used "ifdown" and "ifup" to bring NIC Down and UP.

You should never set a static IP that’s in the range of dynamic IPs...you run the risk of having duplicate IPs on your network.
As I said, if that’s what you did, there’s no reason for the computer to reassign/change the IP address because you changed the type.