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Mike00
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DNS-Problem

Fri Sep 27, 2013 6:28 pm

Hello friends, I have a problem with dns. My topology consist of 2 ISP connected to the router
ISP1 is fiber using OSPF private IP that goes directly to ISP1 and from there ISP route the packets to our branch office, at the branch office are located the dns server/ firewall that translate the private ip to public ip and to the internet it goes

ISP2 is not fiber, its just using a public IP configuration

DHCP configuration Internal LAN. On the dhcp configuration option I configured OpenDNS DNS in case ISP1 fails and ISP2 goes up, internal LAN is protected when it goes though ISP2

Heres the problem, if ISP1 fails, OpenDNS is supposed to protect my internal LAN when it goes though ISP2 and that is not happenig, the only way i can fix this problem is if i do a flush dns or just reboot the router

Is there some kind of configuration that if ISP1 fails automatically ISP2 is protected by OpenDNS
Michael Martinez
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Re: DNS-Problem

Fri Sep 27, 2013 10:57 pm

can you try to use google dns 8.8.8.8 as test basis and let us know the result.
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Mike00
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Re: DNS-Problem

Fri Sep 27, 2013 11:56 pm

The thing is that everytime I disable ISP1, ISP2 start working (good thing) but the DNS of OpenDNS is not, but when i reboot the router, OpenDNS settings start working. For me is weird, I dont know if OSPF is preventing this from happening

I will try adding 8.8.8.8 as a test on monday since the router is at work
Michael Martinez
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Re: DNS-Problem

Mon Sep 30, 2013 8:47 am

how do you have the failover set up?
what do you expect the behavior of the router to be when isp1 is working?
 
Mike00
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Re: DNS-Problem

Mon Sep 30, 2013 4:31 pm

Well, i use the options on the static routes that let me choose the metric, ISP1 = metric 1 & ISP2 = metric 2

What i pretend to do is that if ISP1 fails, ISP2 take over and apply dns from OpenDNS. Ok, everything is perfect, ISP1 fails and ISP2 take over but doesnt apply the dns from OpenDNS. A quick solution for me was to reboot the router and automatically my internal LAN is protected by OpenDNS.

Note: ISP1 connects to a firewall/dns server through ISP1, thats why we are using OSPF
Michael Martinez
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Mike00
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Re: DNS-Problem

Mon Sep 30, 2013 4:35 pm

Also i have configure dhcp for my internal lan with the dns of opendns and i have enable dns server with opendns dns
Michael Martinez
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