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How do you handle public DNS for dual ISP's?

I'm trying to setup a second ISP as a backup link in case my main ISP goes down. How do you handle the public DNS records so my website is accessible if ISP1 goes down?

Basically this is how I thought I needed it setup.

LAN1 -----                            /---ISP1

               \                         /

                ASA5510-------<

               /                        \

LAN2------                            \---ISP2

2 REPLIES
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How do you handle public DNS for dual ISP's?

abrrymnvette wrote:

I'm trying to setup a second ISP as a backup link in case my main ISP goes down. How do you handle the public DNS records so my website is accessible if ISP1 goes down?

Basically this is how I thought I needed it setup.

LAN1 -----                            /---ISP1

               \                         /

                ASA5510-------<

               /                        \

LAN2------                            \---ISP2

Need a little more information to answer that.

Do you have your own address range, or is the "public' IP address ISP allocated (and managed)?

If you've got your own address range, is it hosted on/behind the ASA? And where are your DNS servers located?

If you're going to end up with a different "public" IP address in the event of failure of one ISP, then the only solution I can see if manual change fo the DNS records once you're reconfigured your link. If you have your own IP range, then one link being down shouldn't affect it - you'd be running BGP, and BGP would simply delete the route being advertised via the broken link.

Cheers

How do you handle public DNS for dual ISP's?

well if you are going to have to differnt ISPs and i am assuming you will to differnt Public Ranges for your servers

in this case you will need to discuss with the ISPs to have your DNS setup in redundant way where first IPSp IP is the primary and the second ISP IP is the secondary for DNS Records

becaus if you do not have a Public BGP AS and Public range routed over both ISPs you can not do it other than using the DNS method mentioned above

Hope this help

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