DHCP Server gives out old DNS info

RouterOS General
1

I have a routerboard RB-532 that originally was setup as a spare router for an existing DSL line. We are switching DSL providers so I used this spare for the second path, changed the IP addresses, routing, DNS under IP options etc. Everything works great except…

Doing a DHCP server setup it shows the old DNS addresses, I update them along with the new IP gateway, pools and all appears to work.

Booting a XP computer with DHCP obtains a IP within the range, gateway is correct. Only it still assigns the old DNS server IP’s not the new ones??

Info on the RB-532 (the 128Mb version) running 3.20 firmware 2.18.

Ideas where the old DNS info is coming from and what I need to do to resolve this short of reformatting and reloading.

Thanks

Jerry

2

Check the system DNS settings under /ip dns.

If you havn’t configured any DNS servers in the DHCP server settings I know it uses the system DNS settings instead. Perhaps that’s what’s happening for you as well.

3

IP/dns was updated to the new DNS servers when it was placed in service.

That was the first place I looked.

Jerry

4

Make sure “Obtain DNS server address automatically” is selected under TCP/IP for your workstation NIC.

-Louis

5

Ah, sorry, missed that you wrote that you had updated that.

Well if DNS servers are changed both under “/ip dns” and /“ip dhcp-server network” I don’t understand why it would hand out false DNS servers.

Verify with another client if that gets the new dns servers or not, to make sure it’s not the client problem/missconfiguration.

6

I have tried 3 different windows computers. Get DNS automatically is checked…

7

Just to make sure, do a /export and make sure there are NO references to your old DNS servers.

Try disabling/enabling the dhcp-server.
Try removing the lease entry from /ip dhcp-server lease

8

Good call on the export.. That showed where it was coming from.

I had to remove the network data under DHCP-Server as it still showed up after removing the main server entry.

Will find out for sure tomorrow morning when I’m at the office.

Thanks for the help

Jerry

9

msundman, great suggestion!

I had the same problem!

Never thought to try that!
I was able to correct it, after finding it when doing the “export”