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Web Hosting DNS redundancy

Posted on 2010-09-23
Medium Priority
Last Modified: 2013-12-21

I have a virtual private server with 2 IP addresses on it. I have my own nameservers using ns1.mydomain.com and ns2.mydomain.com but it is configured at the registrar - These point to the 2 IPs on my VPS.

Sometime ago, the registrar had an outage and I want to create some redundancy. So I have another registrar where I can create ns1.anotherdomain.com and ns2.anotherdomain.com and point them to the same 2 IPs on my VPS.

So I presume then I would just add these NS records to any customer domain so that they use the 4 nameserver records I have -

Is this the correct way to create some DNS redundancy.... Any advice much appreciated.


Question by:intangiblemedia
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LVL 21

Expert Comment

by:Julian Matz
ID: 33751263

No, that would not be creating redundancy. You should have a primary and a secondary DNS server. Each one should be located in a different geographic location. The way you have it now, or the way you plan to set it up, is pointless because both nameservers are pointing to the same DNS server, which defeats the purpose of having a minimum of 2 nameservers.

Suppose your VPS server went down. It would mean that your DNS server goes down too, meaning that both nameservers would become unreachable.

Ideally, if the primary DNS server went down, the secondary DNS server would remain up and would take over for the primary nameserver until it came back online.

The primary DNS server is where you manage your host records. The secondary DNS server then fetches these records so that it can serve DNS requests when the primary NS is down or too busy to handle any more requests.

Does that make sense?

Author Comment

ID: 33751623
It kind of makes sense but Im new to this so bear with me....

Firstly I think there are different levels of redundancy right? Of course, having a backup VPS would be ideal which I dont have the funds for right now - But you are correct in that the DNS details, such as A records, MX records, etc... are fetched via the VPS...

So what do you recommend? I use Plesk and a Windows 2003 server - Is there any provider out there that does only DNS management or something?

Thank you!
LVL 21

Expert Comment

by:Julian Matz
ID: 33751691
No problem. Yes, there are DNS service providers, and depending on how many zones/domains you need to manage, there are some that are pretty cost effective, especially if it means you don't need to lease a new server.

My recommendation would be that you try this one:

They let you try their service free of charge, which is perfect if you only need up to 3 zones and have less than 50,000 queries per month.

The next step up would be 25 Domains, 250 Hosts, 10 Templates, and 1,000,000 queries per month at 19 USD per year. For 39 USD per year you can have up to 50 zones.

The benefit of a DNS service provider like this is that they offer both primary and secondary DNS services.

If you really want to manage your own primary DNS, then there are also some secondary-only DNS services available. For example, Nettica offers secondary DNS on per domain basis at 10 USD per yr, per domain.
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Author Comment

ID: 33751720
Thanks Julian,

So - This is what I have

ns1.myprimary.com    > VPS IP1
ns2.myprimary.com    > VPS IP2
ns3.mysecondary.com  > VPS IP1
ns4.mysecondary.com   > VPS IP2

As myprimary.com is hosted with Eurodns, and they went down, it got me into trouble because the actual namserver record wasnt functioning - that is why I want to implement mysecondary.com as it is with another registrar on another network - Am I correct on this?

Then what you say is to actually point these NS to Zerigo instead of my VPS IP1 and IP2?

LVL 21

Expert Comment

by:Julian Matz
ID: 33751783
Yes, at the moment you might have 4 nameservers, but they are all pointing at the same server, meaning you have only point of potential failure with no backup.

You don't even need ns3 and ns4.

You have following options:


ns1 points at VPS IP1
ns2 points at Zerigo

This means you'd be running the primary (master) DNS server yourself, and Zerigo would have the secondary (slave) support. Your VPS would transfer the zone records periodically to Zerigo (ns2) so that both DNS servers are synced.


ns1 points at Zerigo server 1
ns2 points at Zerigo server 2

This means your primary and secondary DNS is hosted by Zerigo, but since Zerigo has multiple servers, you also get redundancy this way. This way, you would log into the Zerigo's control panel to manage your DNS records (A, MX records, etc.)


ns1 points at at Zerigo server 1
ns2 points at VPS IP1

This is basically the opposite to a) - Zerigo is master and your VPS is slave.

Now, you could also add ns3 and ns4 if you wish and have one of them pointing to your VPS in any of the above configurations.

Here is some more information:

In my opinion, however, the simplest solution would be to have all your nameservers point at Zerigo and manage all your DNS zones through them. Since they have multiple DNS servers, geographically dispersed, you would get the redundancy you're looking for.

Then, if you wanted, you could add an additional nameserver and have it point at your VPS in "slave mode" for even more security - for example if Zerigo falls victim to some kind of DDoS attack that might temporarily disable their network (this is just a hypothetical of course, I don't know how well they are guarded against DoS attacks).

Just let me know if you need any more info.

Author Comment

ID: 33751805
ok - but the domain used should be different because if ns1.mydomain.com registrar goes down, which did happen, I lose everthing... That is why i want to use 2 different registrars for my domain names that host the nameservers. Does that make sense?
LVL 21

Expert Comment

by:Julian Matz
ID: 33751843
Well, it's extremely unlikely that if a domain registrars systems go down that it will affect your domains. I have a feeling that the only reason your domain(s) were affected is because your DNS records were hosted by them also, and most likely those DNS servers went down.

Everything else would be stored at the root registries. Think of it like a registrar being an agent - they are providing the domain registration services, but everything else is managed by the root nameservers, which are managed and maintained by IANA and VeriSign. The DNS service the registrar provides is only one additional service they offer in addition to the registration services.

Have a look here:



Author Comment

ID: 33752320
Hi Julian,

Last comment now, to award you points!

It happened a few months ago - I have my main domain name with Eurodns - In their DNS config, I had the ns1.mydomain.com and ns2.mydomain.com pointing to my VPS - In all my clients domains, I configure the NS to be ns1.mydomain.com and ns2.mydomain.com -

When EURODNS went down, ns1.mydomain.com and ns2.mydomain.com died - so all my clients domains could not reference it - this is what I want to prevent, as well as improve the DNS configuration overall - That is why I thought having ns1.anotherdomain.com etc... at another registrar it would help remedy the problem.

Does this make sense?


LVL 21

Accepted Solution

Julian Matz earned 2000 total points
ID: 33755866
Hi Ben,

Yes, that makes sense. Sure it won't do any harm any way, just as long as you make sure you're using at least 2 different physical DNS servers.

Now, if you do decide to use Zerigo, then you could use at least 5 different servers (belonging to Zerigo) plus an additional external secondary/salve DNS server (your VPS).

Your options for this are to either use Zerigo's nameservers (below) or use your own (vanity) nameservers as you have been before.

Zerigo's nameservers:

North America

    * a.ns.zerigo.net - Denver, Colorado, USA
    * b.ns.zerigo.net - Washington, DC, USA
    * d.ns.zerigo.net - Dallas, Texas, USA


    * c.ns.zerigo.net - London, United Kingdom
    * e.ns.zerigo.net - Amsterdam, Netherlands

So, what you could do is this:

Point ns1.mydomain.com at a.ns.zerigo.net
Point ns2.mydomain.com at b.ns.zerigo.net
Point ns3.mysecondary.com at c.ns.zerigo.net
Point ns4.mysecondary.com at e.ns.zerigo.net

And then register any additional nameservers to point at d.ns.zerigo.net and/or your VPS IP1.

Zerigo will have instructions on how to properly set up your vanity nameservers.

Author Closing Comment

ID: 33756068
Above and beyond the remit - thank you so much!
LVL 21

Expert Comment

by:Julian Matz
ID: 33756103
Thanks for the grade! I'm glad I could help.

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