Web Hosting Talk : Web Hosting Main Forums : Hosting Security and Technology : Question about DNS on more than one server

[Adonis]

I've always had only one server, so both my DNS servers were located on this one server. Since last month i have an additional server, and i was wondering how to work DNS with that one.

The problem is this. I run an IRC server at "irc.domain.org" (not the real domain name). I now want to add a leaf at the second server called "us.domain.org". The problem is that the DNS domain is hosted on server1, and both DNS servers are on server1, and it is managed by Plesk. If i add "us.domain.org" in that DNS, then server2 will be reachable, but if server1 is unreachable, then ofcourse server2 cannot be found anymore by that domain... so this would defeat the purpose of server2.

What should i do here? Register a new DNS domain, host those two new DNS servers on server2, and point all records for "domain.org" to server1 (with the exception of the "us" subdomain), and point on server1 the "us" subdomain to server2? In this case the domain whois for domain.org would show 4 dns servers.

Or is there also a way to have my usual DNS domain function on both servers without breaking Plesk or any of my sites on server1?

I've been thinking about this issue and havent got a clue yet. Any advise will be extremely welcome

[KayakStudio]

Originally Posted by Adonis

I've always had only one server, so both my DNS servers were located on this one server. Since last month i have an additional server, and i was wondering how to work DNS with that one.

The problem is this. I run an IRC server at "irc.domain.org" (not the real domain name). I now want to add a leaf at the second server called "us.domain.org". The problem is that the DNS domain is hosted on server1, and both DNS servers are on server1, and it is managed by Plesk. If i add "us.domain.org" in that DNS, then server2 will be reachable, but if server1 is unreachable, then ofcourse server2 cannot be found anymore by that domain... so this would defeat the purpose of server2.

What should i do here? Register a new DNS domain, host those two new DNS servers on server2, and point all records for "domain.org" to server1 (with the exception of the "us" subdomain), and point on server1 the "us" subdomain to server2? In this case the domain whois for domain.org would show 4 dns servers.

Or is there also a way to have my usual DNS domain function on both servers without breaking Plesk or any of my sites on server1?

I've been thinking about this issue and havent got a clue yet. Any advise will be extremely welcome

Have ns1.example.com on the server1 with the dns records for both. then have ns2.example.com on the other server with records for both. Having 2 dns servers declared pointing to one server won't help or hurt you.

is that what you where asking?

[Adonis]

but example.com DNS server is hosted on the 1st server... then the DNS server probably will not be reachable once server1 is unavailable. All domains are hosted on the 1st server, so just moving ns2 to the 2nd server is very difficult, impossible in plesk because thats a plesk 10 domain version, while there's around 100 domains on server1.

Also, how can i move NS2 (or set up NS3) to the 2nd server if its hosted on the 1st one? Doesnt it need hosting first before you can use it? And you can only host it on one... i think.

[KayakStudio]

Originally Posted by Adonis

but example.com DNS server is hosted on the 1st server... then the DNS server probably will not be reachable once server1 is unavailable. All domains are hosted on the 1st server, so just moving ns2 to the 2nd server is very difficult, impossible in plesk because thats a plesk 10 domain version, while there's around 100 domains on server1.

Also, how can i move NS2 (or set up NS3) to the 2nd server if its hosted on the 1st one? Doesnt it need hosting first before you can use it? And you can only host it on one... i think.

you need to declare the dns servers with whoever you registered your domain with.

moving ns2 to the second server isn't hard at all. All you need to do is change that ip address to point to the second server. You should really get a book about bind or something. Having a hosting control panel is great but it doesn't teach you how things work.

Maybe you should consider getting and old computer and setting up a LAMP without a control panel so you can learn about config files and all that fun stuff.

[Xous]

Hi,

The first thing we need to do is clarify what services and software is running on each of these servers.

(Please point out if any of these statements are mistaken.)

server1 is currently both the name-server for ns1.domain.com. and ns2.domain.com.
server1 is currently hosting an irc server with the host-name of irc.domain.com.
server1 is using the plesk control panel.

You now want to add a new server, called server2 for simplicity, and run an IRCD on the server with the host-name of us.domain.com.

If you were to just add an A record on server1 for the us.domain.com to point to server2's ip address then server1 would be a single point of failure.

If you would like to avoid this you could do any of the following:
1. configure server2 as a slave name-server and change the ns2.domain.org. record to point to server2.
2. register a second tld domain and configure a name-server on server2 to provide the name-service for both domains.
3. host your DNS with a 3rd party service to prevent any DNS issues due to a failure of server1 or server2.

Each of these solutions have their own advantages and disadvantages.

1. This can be complicated or easy depending the software you are running on server2. If you are running plesk it should only require about five minutes of configuration. If you are just running bind with no control panel you may have to write a script to update the zone file and restart the bind service on server2 when a change is made.

If server1 or server2 fails a RFC compliant name-server will try a different name-server to get the appropriate information which may result in the resolution process taking slightly longer.

2. This solution removes the complexity of configuration one server to be a slave server but may cause confusion for your users. Is it irc.domain.com, irc.us-domain.com, irc.domain.us, etc.

This has the added benefit that if you forget to renew one of your domains that at least some of your customers are able to find your site. (aside: you do renew your domains for at least two years at a time, right?)

3. Using a 3rd party DNS service (or managed DNS service) allows for your DNS to be completely independent from your servers and generally provides better service than you can provide yourself. That said, you probably do not need the extra few milliseconds or 1-2 seconds that geographically dispersed name-servers will provide. (If you anticipate having lots of overseas visitors this may be useful)

The primary disadvantage is the cost (DynDNS.com for example charges $27.50/year). This will also be a slight pain as DNS changes in Plesk will not take effect. You must manually make the changes in your providers control panel.

The choice I would go with at this stage would probably be with the first option. If you are only now just adding a leaf server you probably do not have the amount of users to warrant managed DNS. I would recommend the second option if you feel that your visitors are savvy enough to know why they should use the second domain.

[Adonis]

Thanks for your elaborate answer Xous. I would love to go with option one, but moving NS2 to server2 is not my desire, as there are lots of domains connected to that one, which are all on server1. Only one domain will be on server2.

So is it possible to create a NS3 on server2, have it act as a slave and add it to the IRC domain.com as NS3. This way, the IRC domain has 3 nameservers instead of 2. Also, this would only require me to update one domain instead of 100 which would be the case if i were to move NS2. All these domains will only have NS1 and NS2.

Would this work as well?

[Xous]

Hi,

Yeah that should work fine but I would recommend removing ns2 from the list of name-servers for that domain because if server1 ever went down then the resolvers may end up trying to connect to ns1 to find it down and then try ns2 and find it down. This would add a bit of unwanted delay.

If you get it configured right you should only need to update the domain settings on server1. server2 will pick them up via zone transfers.

[Adonis]

Okay and just to make sure here... my dns domain is physically hosted on server1. That means i do not have to also physically host it on server2... just register NS3 with the registrar and add it?

[Adonis]

This issue is eating me up alive... i just posted the following on the plesk forum, maybe there are plesk users here on WHT that have experience with slave DNS in Plesk:

I don't see how to create a slave DNS server on a 2nd plesk server. What i did was the following:

- Added the nameservers at the registrar

- Created the DNS domain on server1 without selecting any hosting options.

- Setting up NS1, pointing at IP address on server1, and NS2 at IP address at server2.

That all went fine, but when i create a domain on server1, its record is not being copied to server2 (where NS2 is). The only way i can create records there, it seems, is by also creating that same domain on server2 and then changing that domain's DNS settings to "slave".

I don't think that should be right, because then 1 domain costs me two plesk domain slots. So 100 domains on server1 will also cost the same number of slots on server2, while the domains arent even physically hosted there.

Maybe i'm missing the point here... how do i get slave DNS (NS2) to work on a 2nd server without creating those domains in plesk?

[gnusys]

Just register a ns3.xxx.com as a glue record ( child nameserver) at your domain registrar by passing over the ip of the second server. If you are comfortable with editing named.conf or zone files.create the domain.org zone manually ( try adding the zone in named.conf.local and include this file in your named.conf ;if you are in Debian GNU/Linux..you already have that file )

Or if you have plesk on the second server just create a domain.org in your plesk and adjust the zone file details from "DNS settings"

The more the number of nameservers you have the better. No one has restricted the number of nameserver to 2!

[Adonis]

Or if you have plesk on the second server just create a domain.org in your plesk and adjust the zone file details from "DNS settings"

That costs me another Plesk slot, eventho it will only be used for the DNS and not for hosting.

But i was wondering... i was always tought that in order to make a DNS work in Plesk, you needed to first add hosting for it, and assign subdomains for the DNS servers (ns1, ns2, etc). Is this actually true? Since you also assign these subdomains at the registrar as glue records.

Do i actually have to add this domain and subdomains to Plesk in order to make it work, or are the registrar's gluerecords enough?

[gnusys]

I gave the plesk idea just incase you had plesk on the second one .Just create a named.conf entry and a zone file. You can actully copy the same from the first server

And practically! you dont have to add A records for the NS records and it still takes the A record from the glue record at the TLD zone. But You MUST! inoder to comply to DNS principles always must supply A records for hosts that you are authoritative for including the ns.domain.com as the ns comes under domain.com and therefore you are authoritative for it

As far as all other subdomains/hosts are concerned (other than the ns hosts for which you have provided the glue record).YES you have to provide entries in the zone file because the parent nameservers just gives a referral to your nameserver for any hosts under your zone

In short..it still works if you dont provide A records for ns..ns1..etc for which you have glue ..but it is strongly advised to provide the A rcords

And it does not work if you havent provided A record for other regular hosts like irc.yourdomain.com

Hope u got the point

[Adonis]

I have plesk on that server, but its only a 10 domain version instead of the 300 domain one i have on the other one, thats why i really would like to save Plesk slots to use those for real hosting accounts. It's also a bit nonsense to have 2 plesk licenses for the same domain, just to make a DNS record... but that's a question i've got open with the Plesk forum.

So i can just add a record like the following to named.conf, and it will automatically receive the DNS records for that domain from the primary DNS server?:

zone "domain.org" {
type slave;
file "domain.org";
masters {
10.0.0.1;
};
allow-transfer {
192.168.2.1;
common-allow-transfer;
};
};

Even if it works, plesk will probably overwrite that file again with its default values (domains that are defined inside plesk). Plesk has a habit of overwriting anything that it uses with no regard to any changes that are already there.