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  1. #1

    INQUIRY on DNS/WEBSERVER FAILOVER

    Hi and Good day!

    I would like to inquire about DNS/Webserver Failover. Here is the situation. I have subscribed to a webhosting company with a VPS and Dedicated server and I already implemented DNS clustering on both servers. I want to have a redundant/clustered webserver in different locations geographically. What necessary steps I need to undertake? I have a list of steps but I want ot confirm if these steps will answer my requirement/goal to have an ALWAYS AVAILABLE and ACCESSIBLE websites if ever my primary webhosting company goes down (facility, network or server instance). Please see below steps:

    1. Get an external server from other webhosting company Preferred to have cPanel/WHM in server for easy manipulation of records)

    2. Copy the websites data of all domains from 2 webservers (from main webhosting company) to the external server (this will serve as my backup webserver)

    3. Register another nameserver associated with the IP address of the external OR use the existing DNS address of the external server

    4. Implement DNS clustering on our 3 Liquidweb webserver and the external server.

    5. Modify the DNS address of all domains in the registrar (godaddy.com) to add the additional DNS address of external server.

    6. Re-create the DNS zone file of the 2 webserver to add the NS Address of the external server, recreate DNS zone file of external server to have identical DNS zone file from 2 webservers. (Server running at the same time)

    7. In case there is interruption on main webhosting company facility or downtime webservers, modify the zone file of external server and point the A records of all domains to point to the main IP address of the external server and lower the TTL value to 300

    8. If and then the main webhosting company server/nameserver failed but server/WHM is Still accessible it is recommended to modify also the DNS zone file and point the A records of all domain to the main IP address of the external server so that if the nameserver does start again and become available all nameservers will be pointing to the same IP address.

    9. If the server is not accessible during the downtime and not able to modify the DNS zone file to point to the IP of the external server, then these 3 servers goes up and become available, modify the DNS zone file of the external server and point the A record back to the IP of the webservers of the main webhosting company.

    By the way, I am managing my DNS via godaddy.com

    Is there any other appraoch you can recommend?

    Your utmost attention and reply will be highly appreciated.

    Thank you very much.

  2. #2
    Hello!
    I suppose you need first of all try to do something in this direction with your web hosting provider
    We are here do not see full picture...
    Good luck

  3. #3
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    By DNS failover I think you are referring to the DNS TTL solution for the web servers? This solution is flawed and ineffectual for reasons stated in a nearby thread. You should use loadbalancing

  4. #4
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    What you are wanting to do isn't a bad idea for something that needs to stay online but the way you're trying to go about doing it doesn't sound effective. You may want to contact a company that is familiar with High Availability offerings and is reputable in the industry to get their advice.
    Michael Denney - MDDHosting LLC
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  5. #5
    Join Date
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    I would recommend you looking into DNSmadeeasy.com they offer some awesome anycast DNS setup with failover and such. It is also pretty cheap as well.
    Eleven2 Web Hosting - World-Wide Hosting, Done Right!
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  6. #6
    Join Date
    Oct 2007
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    Quote Originally Posted by Collabora View Post
    By DNS failover I think you are referring to the DNS TTL solution for the web servers? This solution is flawed and ineffectual for reasons stated in a nearby thread. You should use loadbalancing
    Once again I would like to see actual evidence that this does not work because I have many clients that use this everyday and it always works.
    So, really all I want is stats. Please use any good DNS service. Do a dig against your ISPs resolving name servers, change the IP, wait for the TTL, and then query again. Show me it "not" working.

    I just tested it with AOL and it worked perfectly.
    I just tested it with Verizon and it worked perfectly.
    I just tested it with Cox and it worked perfectly.

    So.... come one here... show me this "not" working.

    Give me an ISP that ignores TTL that are over 180 seconds.

  7. #7
    Thank you very much GURUS for the replies. I really appreciate it. I already read some other articles about service providers that offers DNS Failover, the likes of DNSMadeEasy, UltraDNS, and Nettica, etc. I was hoping that If there's any way that I can do it manually for obvious reason of cost involvement, but if and then these providers will addressed my concern/goals of having a redundant/clustered webserver in different locations geographically and ensuring to bring our customer at least 99% websites uptime I will leaning towards getting their service.

    Thank you very much.

    Best Regards,

  8. #8
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    You can do it manually, however those services will monitor primary server and when a down state is detected will automatically update dns A record for secondary server. A human does not have to be around to make the switch.

    Using this method, and best TTL settings, you will lose current visitors and future visitors over the next several minutes. Up until after 30 minutes or so you will regain almost all of the future visitors. This is because IE will remember old IP for 30 minutes and Firefox for about 1 minute (each will take a couple minutes after that to recover from error). There will be some users that will not be able to access your site for up to 48 hours because some ISPs and private networks do not honor TTL and will configure their DNS caching servers (and/or web proxies) according to what's best for their networks
    Last edited by Collabora; 08-27-2009 at 09:20 AM.

  9. #9
    Join Date
    Oct 2007
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    446
    Quote Originally Posted by Collabora View Post
    There will be some users that will not be able to access your site for up to 48 hours because some ISPs and private networks do not honor TTL
    Ok... Please provide one ISP that forces a 48 hour TTL.
    Never have seen this happen.... No where in the United States at least.

    Quote Originally Posted by dyep View Post
    Thank you very much GURUS for the replies. I really appreciate it. I already read some other articles about service providers that offers DNS Failover, the likes of DNSMadeEasy, UltraDNS, and Nettica, etc. I was hoping that If there's any way that I can do it manually for obvious reason of cost involvement
    Ok we sell try to push UltraDNS a lot because the service is overall really good, and you can make a huge markup on their services. But yes I agree, several $k per month is a lot for some companies (but still a drop in a bucket for any decent size company). Charge a company $5k per month to give their website extra uptime is nothing to them. Big CXOs at companies don't even consider that a cost.

    But DNS Made Easy is costly??? You serious? It's like a $5 add-on per year for failover.... If you can not afford that, then skip that one cup of coffee once a year and you just paid for it. Or drive to a state that pays for recycled cans. Find one emtpy soda can a day (5 cents per day) and you will be able to pay for DNS Made Easy and still have enough to pay for an extra cup of coffee at the end of the year. If you collect two cans... make sure you treat me to the second cup.

  10. #10
    Join Date
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    Quote Originally Posted by Collabora View Post
    By DNS failover I think you are referring to the DNS TTL solution for the web servers? This solution is flawed and ineffectual for reasons stated in a nearby thread. You should use loadbalancing
    You mean the thread that had to be closed down by a moderator because it turned into personal attacks? The failover mechanism, which includes DNS failover, works very well. We have many customers that are very happy with the results / uptime.

    Regards
    UNIXy - Fully Managed Servers and Clusters - Established in 2006
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    www.unixy.net - Los Angeles | Houston | Atlanta | Rotterdam
    Love to help pro bono (time permitting). joe > unixy.net

  11. #11
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    Quote Originally Posted by UNIXy View Post
    You mean the thread that had to be closed down by a moderator because it turned into personal attacks?
    Haven't seen that one

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