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From what I know DNS is a service that translates domain names into IP addresses.

I have noticed something on some small networks in small companies when they used routers as a switches.

modem---router(A)---router(B)---PC

Router(A) 192.168.0.1

Router(B) 192.168.1.1

If you have two routers on the same network and both of them have enabled DHCP but in a different subnet mask, and you want to access the page of router(A) or (B) you must enter the static DNS inside your PC like this

DNS 192.168.0.1
second DNS 192.168.1.1

If not you will be enabled to access one of them. I know it's a wrong configuration but it works!

My question is why ? DNS not works like that!

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  • I'm struggling to make sense of what exactly you are asking. It doesn't make much sense to have two routers in between a modem and a client, and the fact that you do should have no significant effect on DNS. The only problem I can think of is DHCP, but routerB shouldn't be forwarding DHCP traffic from the routerB-PC link to the routerA-routerB link. Could you edit your question to include a fuller network diagram that shows a more realistic example?
    – user
    Aug 19, 2015 at 20:24
  • I have discovered by mistake this thing, when I was figure out a network with two routers, both have DHCP service ON, I want to access router (B) but the PC take the DHCP from the router (A), so it was hidden in the network, by setup the DNS to static DNS on my PC and enter both addresses of my routers 192.168.0.1 & 192.168.1.1 as first and second DNS, I was enabled to access both of them without any problem, why is that happened I still not know exactly, but GeekyDaddy answer my question, but still want to know more about it
    – Narzan Q.
    Aug 19, 2015 at 20:38

1 Answer 1

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Some routers have the ability to turn into switches and therefore don't have to have DHCP enabled and all the machines can stay on the same IP range. This would eliminate your problem.

But to answer your question, Router A and Router B have a table containing all the machines and the best routes to access a computer attached to it. For your computer to find a machine at your work it checks with one router then with the other. There is a good chance that one router doesn't know about the machines on the other router. This is why both router are listed as DNS servers.

It's not a wrong configuration, but not an optimal. It does allow segregation of machines. For example accounting department plugs into router A, while sales plugs into router B.

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    If you are able to get into the configuration of Router B and turn into a switch. Do the following: Turn off DHCP and assign it an IP address that's out of the range of the DHCP from router A like 192.168.0.2. Plug router A into the a LAN port of router B, don't use the WAN port in router B. All computers attached to router B will be assigned IP address from router A.
    – GeekyDaddy
    Aug 20, 2015 at 20:25
  • Amazing answer :)
    – Narzan Q.
    Oct 7, 2015 at 10:01

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