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    DNS Disaster Recovery - How to Easily Update DNS When Server Goes Down?


    I have a web server with about 20 websites and worry about what will happen if the server goes down. If the server fails and I need to restore an image to another server with a differnt IP address, how can I quickly reset the DNS "A" records to use the new IP address of the new server (I do have access to each domain registrar to change the DNS "A" record).

    Can I enter multiple "A" records and it will failover to the second server (I do not want any traffic to the second server unless the first server is down)? Is there an intermediary DNS server that can help?
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    Multiple A records will be delivered both at the same time. So that's more of a round robin pseudo load balancing thing than a back-up plan.

    You best bet is to have a slave server hosted off site in a reliable system. Like a server with Amazon web services or some sort of server hosted company. I use Amazon for a slave and they had a deal to get a free server for 12 months. If the master goes down, the slave will still answer authoritatively until the expiry ttl runs out. That should give you time to recover "most" situations.
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    By the sounds of it, you're concerned about your web server failing, and having to cut over to a new web server which would involve updating 10+ DNS A records.

    You could possibly use CNAME records for all your domains to point to a single "master" A record which would hold your live web servers IP address. If you set the TTL low on the A record, say 600, then in the event your web server blows up you would only have to alter one A record (the "master"). You would update DNS and point this A record to the failover web server and because of the low TTL it should be up and running in just 10 mins (600 seconds).
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    Slave Server


    I am not familiar with a slave server. Can a Slave Server with if my primary server is hosted at GoDaddy? Does the slave server receive the website request if the primary is down, even though the host "A" record has not been changed?

    Originally Posted by Eddie_D
    By the sounds of it, you're concerned about your web server failing, and having to cut over to a new web server which would involve updating 10+ DNS A records.

    You could possibly use CNAME records for all your domains to point to a single "master" A record which would hold your live web servers IP address. If you set the TTL low on the A record, say 600, then in the event your web server blows up you would only have to alter one A record (the "master"). You would update DNS and point this A record to the failover web server and because of the low TTL it should be up and running in just 10 mins (600 seconds).

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