how to configure secondary / slave name server

mfoley · 11-19-2017, 09:53 PM

Thanks for your response I'm getting a timeout. That link has useful information, but I'm not caring about fallback DC control just yet. I have only one domain controller. I'm just looking for backup DNS. Here's what I've been told could be part of the problem. As mentioned, I have 2 Internet facing servers, both also have a 2nd NIC for the LAN. Host A is the AC/DC, DNS server and DHCP server. It is also the LAN gateway at 192.168.0.2. Host B is the backup DNS. Both are Linux and the connection timeout problem is not limited to Windows workstation.

I was told that if that the gateway goes down, no host on the LAN can get to the Internet. I'm thinking about installing a router upstream from both of these hosts and designating it as the gateway at 192.168.0.1, taking hosts A and B off dual-homed an using one NIC in each as 192.168.0.2 and 192.168.0.3, respectively. Would that work?

bathory · 11-20-2017, 04:08 AM

Quote:

I was told that if that the gateway goes down, no host on the LAN can get to the Internet.

That's right.

Quote:

I'm thinking about installing a router upstream from both of these hosts and designating it as the gateway at 192.168.0.1, taking hosts A and B off dual-homed an using one NIC in each as 192.168.0.2 and 192.168.0.3, respectively. Would that work?

You'll still have a "single point of failure".
If 192.168.0.1 goes down none of the 2 nameservers will work. That's why it's good practice to have the 2 (or more) authoritative nameservers on different nerworks.

mfoley · 11-20-2017, 01:25 PM

Quote:

Originally Posted by bathory

You'll still have a "single point of failure".
If 192.168.0.1 goes down none of the 2 nameservers will work. That's why it's good practice to have the 2 (or more) authoritative nameservers on different nerworks.

Well, that's OK for now. If 192.168.0.1 goes down this office is pretty much screwed anyway. Somewhere, there's going to be a single point of failure. Upstream from the proposed 192.168.0.1 is the Time-Warner/Spectrum fiberOptic modem - also a single point of failure. So, that's not my main issue.

I'll try the idea of creating a 192.168.0.1 router upstream this Friday when everyone is off. I'll report back results.

mfoley · 11-21-2017, 12:53 AM

Here's a thought. Instead of putting a router up-stream from the Internet-facing host and using that as the gateway, could I not just use the ISP supplied gateway? So, if my subnet is 192.168.0.0/24 and my ISP's gateway is 98.102.64.120, what if all the hosts on 192.168.0.0/24 specified that as the gateway. Would that solve the problem of the current 192.168.0.1 gateway going down?

If so, how would I specify that. Is that the 'option routers' parameter in dhcpd.conf?

bathory · 11-21-2017, 03:38 AM

Quote:

So, if my subnet is 192.168.0.0/24 and my ISP's gateway is 98.102.64.120, what if all the hosts on 192.168.0.0/24 specified that as the gateway. Would that solve the problem of the current 192.168.0.1 gateway going down?

Don't you still need a router to route traffic from 192.168.0.0/24 to 98.102.64.120?

mfoley · 11-21-2017, 07:23 AM

Quote:

Originally Posted by bathory

Don't you still need a router to route traffic from 192.168.0.0/24 to 98.102.64.120?

I don't know. Does a gateway have to be routable from the 192.168.0.0/24? This is new territory for me.

bathory · 11-21-2017, 08:50 AM

Quote:

Originally Posted by mfoley

I don't know. Does a gateway have to be routable from the 192.168.0.0/24? This is new territory for me.

The gateway needs to be reachable somehow. So if it's not on the same subnet, you have to define a static route to it.
Take a look at this, or start reading about the route and/or ip route commands.

Regards