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I'm having 2 ISPs, need to balance traffic between the internal users ...

Firewall is SRX210

The question is: Each ISP has there own DNS, how to make the dns resolving based on the used ISP?

Example:

If ISP1 goes down, how to prevent DNS-clients from continuing the trying to resolve using ISP1 DNS ? and how to force using ISP2 DNS ?

masegaloeh
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MohyedeenN
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1 Answers1

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The question is: Each ISP has there own DNS, how to make the dns resolving based on the used ISP?

Why do you care? The last time I used an ISP DNS was many many years ago. Run your own or go to the public Google DNS Servers. Finished.

ISP's sometimes do crazy stuff with their DNS to "Improve service" - stuff that may break applications.

If you avoid them, then you go back to the normal problem of "how do you load balance any request between ISP's" and "how do you realize an ISP is down", which you have to solve anyway.

As such, your problem is a non-problem, coming only from using an ISP based DNS to start with.

kasperd
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TomTom
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  • Does't enhance the performance to use ISP DNS ? with this the resolve is different and traffic is directed to their caching servers for example ?.... Advise plz – MohyedeenN May 16 '15 at 08:36
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    @MohyedeenN Yes some domains will provide responses optimized for the ISP whose DNS server you are using. As such using the DNS server from one ISP and connecting through the other ISP will give reduced performance on some sites. It is possible, that it may even break, but that should be rare. If you use `google-public-dns-{a,b}.google.com.` as your DNS servers, Google will have more information to base their load balancing on. So for accessing Google, that should perform as least as good as using the ISP servers. – kasperd May 16 '15 at 08:54
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    @MohyedeenN I agree with TomTom, that which DNS server to be using shouldn't be your primary concern. The best performance and reliability would be achieved by sending queries to two different in parallel and use the first which replies. Similar you want the client to make two TCP connections in parallel going through separate ISPs. – kasperd May 16 '15 at 08:56
  • OpenDNS is also an alternative to Google's DNS servers. – muncherelli Jun 17 '15 at 04:20