Solved dns ip conflicts on routers

March 31, 2015 at 04:54:36
Specs: Windows 7
I have two networks each connected on different router with different ip addresses etc but same dns ip address and i am having dns conflicts always Is that might be the cause or its normal to have same dns addresses on all routers on the network????

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✔ Best Answer
April 1, 2015 at 08:21:31
yep your ip addressing is wrong.

You can't have
IP Address: 91.151.7.170
Gateway: 91.151.7.161

then Vigor.router [192.168.1.1]

then back to 91.151.7.161

You should not be using public ip on your lan but private ip.
http://en.wikipedia.org/wiki/Privat...

Topology should look like this:
vigor<>router1
vigor<>router2

Ip should look like this:
vigor[192.168.1.1]<>[192.168.1.2] router1 [192.168.2.1]<>pcs in the 192.168.2.x subnet
vigor[192.168.1.1]<>[192.168.1.3] router2 [192.168.3.1]<>pcs in the 192.168.3.x subnet

the left side of each router is its wan port. The right side is its lan port connecting to a switch since with the subnet mask you were using you are looking at around 30 pcs off of each router.

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message edited by wanderer



#1
March 31, 2015 at 05:52:29
The same ip address on two devices in the same network is never preferred in my opinion. You never know which of the same ip addresses you will contact first.

::mike


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#2
March 31, 2015 at 06:50:49
Each device on a network must have its own unique ip address - otherwise conflicts...

You have two routers with computers etc. attached to each router. Each router must have its own ip address.

ip addresses are typically in the format of 192.168.x.y

For all devices on your network be it routers, computers, printers etc, " x " must be same value; " y " can be anything from 2 - 253.

Typically router-1 might be 192.168.0.1; and router-2 - 192.168.0.2.

You would not normally use 192.168.0.1 or 192.168.0.254 on a second or more router Sharing a lan with another router); even if its default homepage address is one of those. They are reserved addresses for the router's homepage/admin etc..

Depending on how you are using the each router, particularly the second - or more - router(s), depends on how you set up those additional routers re' ip addresses it/they provide for devices attached to it/them.

This link may help explain/clarify it all more clearly:

http://www.wikihow.com/Connect-Two-...

Also for printers at least - generally wise(r) to reserve a specific address to its mac address; so that whenever the printer is powered up it doesn't get different ip address to the previous occasion... Printers prefer a static/reserved ip address.


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#3
March 31, 2015 at 08:52:25
this is how i configured the two routers

Students router 1

IP Address: 91.151.6.214
Gateway: 91.151.6.193
Subnet: 255.255.255.224

DNS1: 91.151.2.5
DNS2: 8.8.8.8

Office router 2

Port A24 – 5Mb

IP Address: 91.151.7.170
Gateway: 91.151.7.161
Subnet: 255.255.255.224

DNS1: 91.151.2.5
DNS2: 8.8.8.8

Port A25 – LAN Uplink to 5th Floor
Port A26 – LAN Uplink to 4th Floor

message edited by mangwe263


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Related Solutions

#4
March 31, 2015 at 15:45:31
There is no such thing as a dns conflict. IP conflict yes but what you have is a subnetting miscalculation.

first routers subnet mask gives 91.151.6.192 - 91.151.6.223
second routers subnet mask gives 91.151.7.160 - 91.151.7.191

Unless you have a subnet between these routers and the internet that contains a subnet that has this dns server at 91.151.2.5 you have listed a invalid dns server.

Now if you have a subnet following the same subnet mask you are using on the other two so you have 91.151.2.0 - 91.151.2.31 then you should have no issues getting both segments to your dns server

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message edited by wanderer


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#5
April 1, 2015 at 00:13:16
Thanks wanderer but am getting lost on your last paragraph can you simplify a bit, also the ISP provided the above details but like what you are pinpointing I will have to recalculate the subnetting or to redesign the network from scratch

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#6
April 1, 2015 at 07:02:59
91.151.2.5 resolves to
ns2.mp2000.net
so it is a public dns server

Point I was making is you have to have a path to it since due to your ip addressing it can't reside on either network.

From either network do a nslookup google.com and post the results for review.
Do a tracert 91.151.2.5 an post those results also. Thx

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#7
April 1, 2015 at 08:02:30
wanderer

tracert 91.151.2.5

Tracing route to ns2.mp2000.net [91.151.2.5]
over a maximum of 30 hops:


1 103 ms 1 ms 86 ms Vigor.router [192.168.1.1]
2 96 ms 41 ms 3 ms 91.151.7.161
3 61 ms 5 ms 3 ms 509-ge0-3-cr3.thn.as42004.net [91.151.7.205]
4 119 ms 25 ms 8 ms 91.151.0.79
5 13 ms 4 ms 3 ms ns2.mp2000.net [91.151.2.5]

Trace complete.


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#8
April 1, 2015 at 08:21:31
✔ Best Answer
yep your ip addressing is wrong.

You can't have
IP Address: 91.151.7.170
Gateway: 91.151.7.161

then Vigor.router [192.168.1.1]

then back to 91.151.7.161

You should not be using public ip on your lan but private ip.
http://en.wikipedia.org/wiki/Privat...

Topology should look like this:
vigor<>router1
vigor<>router2

Ip should look like this:
vigor[192.168.1.1]<>[192.168.1.2] router1 [192.168.2.1]<>pcs in the 192.168.2.x subnet
vigor[192.168.1.1]<>[192.168.1.3] router2 [192.168.3.1]<>pcs in the 192.168.3.x subnet

the left side of each router is its wan port. The right side is its lan port connecting to a switch since with the subnet mask you were using you are looking at around 30 pcs off of each router.

Answers are only as good as the information you provide.
How to properly post a question:
Sorry no tech support via PM's

message edited by wanderer


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#9
April 1, 2015 at 08:26:57
thanks for your valuable response

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#10
April 1, 2015 at 12:02:09
Glad to help and best of luck!

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