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DNS failover / redundancy

Discussion in 'Bind / DNS / Nameserver Issues' started by cz1179, Jan 5, 2005.

  1. cz1179

    cz1179 BANNED

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    Simple question. I have my domain's dns zone on a server (original shared hosting server) but it points to my new dedicated server (used for CPU resources). So the dns zone uses ns1/ns2 (again on shared server pointing to #2 server).

    How do I set up the domain so that if server #1 (shared) goes down, my site stays up? I was thinking adding ns/ns0 to the nameservers of that domain (ns/ns0 is located on server #2 of course). So if I apply the ns/ns0 IP's and add ns/ns0 to nameserver summary would that be considered at least a workable method for dns failover for that domain?
     
  2. lost

    lost Well-Known Member

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    the easiest and best thing to do is 'outsource ' your dns.
    take a look here: http://www.dnsmadeeasy.com/u/19258

    inexpensive, works well with ttl set as low as 5 sec.

    L
     
  3. cz1179

    cz1179 BANNED

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    I can't do that honestly, (if I understand correctly). I already have ns1/ns2 setup on the shared server for many clients and don't want any downtime whatsoever. Perhaps I'm not understanding how the outsourcing works so forgive me
     
  4. dalem

    dalem Well-Known Member
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    cluster server 1 and 2 together

    from reading your post I am asuming your are keepping both servers (correct me if i am wrong)
    use an ip from server 1 for ns1 and use a ip from server 2 fro ns2 that way is server 1 goes down the dns on server 2 will still resolve loading the site

    if you not keeping server one just dns cluster the two servers together and change the ip's to ips on server 2 down time 0 :)
     
  5. jdonoso

    jdonoso Well-Known Member

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    One question and sorry if this sounds newbie, but wanted to be sure.

    Once the dns clustering is done, for it to work correctly, you MUST have the same accounts you have on server 1 in server 2. Correct?

    Please advise.

    Best regards,
     
  6. dalem

    dalem Well-Known Member
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    just the DNS :) and it will automaticly sync to the zone files
     
  7. jdonoso

    jdonoso Well-Known Member

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    Thanks dalem,

    So, if I understood correctly, on server 1 I have hosted 40 accounts, and on server 2 nothing. If I set sync dns, if server 1 fails, it automatically starts serving web pages using dns supplied in server 2? But this also applies as long as the server 1 is running and the failure only applies to its dns service, right? :confused:

    Is that correct?


    Best regards,
     
  8. dalem

    dalem Well-Known Member
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    yes as long as at least one of the IP's is on server 2

    it will not serve the webpages only the domains will resolve its clutered DNS not a clustered webserver
     
  9. electric

    electric Well-Known Member

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    Couple of questions:

    1) I've heard that the cPanel DNS clustering system is really bad. Can you tell me if this is true? Does it work well? (Easy to use, and is VERY reliable.)

    2) Does DNS clustering add a lot of extra server processing to each server?

    Thanks!
     
  10. dalem

    dalem Well-Known Member
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    I have used it ever since it was an option for cPanel I do not notice any extra server loads it has worked with no troubles

    they do however cPnel only recomends not running to many servers clustered (how many is to many I do not know) I have had up to 4 servers clustered with no problems

    curently have 3 clustered now
     
  11. mr2jzgte

    mr2jzgte Well-Known Member

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    True clustering where one or more server goes down and sites remain up.. Then speak to me... but it's not cheap.. You need a minimum of 5-6 servers to do it properly.. it can be done with 3-4 (for simple load balancing with minimal fail over)

    DNS Clustering - Meh. Its crude and I've been using it for a while. Simple rsync scripts between 4 servers which are updated every hour. Basically syncronises named.conf and /var/named on all 4 machines. restarts named and off it goes serving requests...

    never had a problem with cpu load and we have 3000 clients + umpteen amount of domains.

    It would be possible using heartbeat + ldirectord, + 2 servers in diff locations.

    scenario

    Machine 1 - Main CPanel Machine
    Machine 2 - DNS / Secondary MX.

    Assumes that:
    Each domain name hosted has the following ns records
    ns1.domain.com
    ns2.domain.com
    And mx records
    mx1.domain.com
    mx2.domain.com

    Using ldirectord and heartbeat you can determine when a server goes down. This restarts named with a different config than what it would normally start with (this can be setup with a template so that any requests get the same results ) i.e someone requests the records for a domain. Your server knows that the other server is down and has restarted the named server with a blanket config so anyone requesting records gets the ip/cname of ns2.domain.com

    this points to a webpage which says system maint or system unavailable.
    likewise for the mx records...

    I can explain in more detail if anyones interested but that would be the simplist and cheapest "fail over" solution available.

    james@austdomains.com.au
     
  12. wantmaker@spider

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    From Whm?

    Hello and thanks in advance for helpful input

    The Question
    Is there any way to setup an actual domain name system with WHM-only access to multiple accounts?

    The Details
    I was admiring the intentional (designed?) DNS problem (primary.DNSMachine = secondary.sameDNSMachine) and was trying to manually correct the issue using the WHM on two different reseller accounts. I thought it was going well when the "Add a DNS Zone" page asked for "IP" and "Domain" (thinking it would take the SOA IP and go fetch the records), but -- as I'm sure you guys already knew -- it just setup another primary zone.

    So, is there any non-duel-zone-headache-causing-synchronization way to actually have a real live on-a-different-network (or at LEAST on a different machine) secondary if you only have WHM access? Is there a "Create Secondary" option that's not enabled on mine?

    Thanks again.
     
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