Under my present host I have 3 name servers.

In looking for a potential new host, I note that some have only 2 name servers. In fact, I may be wrong but I seem to remember one host that only had one.

Sheesh, I know I win the loving cup for dumb question of the month, but is there any significance to the number of nameservers???

Aloha from Hawaii,
bellgamin

The typical set up is 2 name servers. Yes, you really only need one, but the secondary name server is for redundancy and recommended. Some hosts have more than 2 name servers, and that doesn't hurt either. There's no one right way to do this, but if you are a professional web host, you will have at least 2 name servers.

I seem to remember that 2 nameservers was intended to be used for redundancy no so long ago, but now-a-days any hosts also host both nameservers on one machine. In fact many host it on the same machine as your site, which is just like having one nameserver in effect. You may wish to search some information on DNS or nameservers on this forum. On the other hand, you can always use a 3rd party dns service such as www.everydns.net
www.granitecanyon.com

Redundancy is useless if you run the DNS server on the same server that web sites are hosted on. It's only useful if you have more than one server using the same DNS server or load balancing between several servers.

RFC 2182 "Selection and Operation of Secondary DNS Servers" is a good read for this topic... On the topic of additional name servers a couple of key points it states are: 3. Secondary Servers

A major reason for having multiple servers for each zone is to allow
information from the zone to be available widely and reliably to
clients throughout the Internet, that is, throughout the world, even
when one server is unavailable or unreachable.

Multiple servers also spread the name resolution load, and improve
the overall efficiency of the system by placing servers nearer to the
resolvers. Those purposes are not treated further here.

With multiple servers, usually one server will be the primary server,
and others will be secondary servers. Note that while some unusual
configurations use multiple primary servers, that can result in data
inconsistencies, and is not advisable. ... it goes on to say .... They should also be connected to
the net via quite diverse paths. This means that the failure of any
one link, or of routing within some segment of the network (such as a
service provider) will not make all of the servers unreachable. Some registrars for tlds such as .fr, .ke, and .de require the name servers be placed on totally separate networks for the above reasons. In order to host tlds such as these, not only will you need to have more than one name server but you will also need to place each one on a separate network all together.

Also .. lets not forget that .. most hosts have 2 or 3 DNS servers .. but they are in ONE phisical server ;) ..

Re: having secondary dns on a seperate network....

Seems to me that you'd then need THREE networks available to you. One to host websites, one to host primary dns, and one to host secondary.

Otherwise, if you only had two, and your primary dns/website network went down, the dns request would roll over to the secondary dns network, which would resolve the address to your primary dns/website network, which is down, so nobody could get to your websites anyway.

Or am I overlooking something?
:confused:

I was doing great and then Alareach's comment threw me for a loop. Namely...

Originally posted by Alareach
On the other hand, you can always use a 3rd party dns service such as www.everydns.net
www.granitecanyon.com

Duhhh... I thought that the host for my website HAS to be the one providing my dns service. In fact, the means by which I activate a new domain is to go to my registrar and enter the host's nameservers for my domain.

Right??? Right???

So how in the world could/would someone make use of a 3rd party for dns service?

By the way, FQ now hosts one of my domains. Super great folks. Seeing Deb's post here was like -- I dunno -- a visit by the queen, maybe.
:cartman:

Otherwise, if you only had two, and your primary dns/website network went down, the dns request would roll over to the secondary dns network, which would resolve the address to your primary dns/website network, which is down, so nobody could get to your websites anyway.

Or am I overlooking something? I believe a lot has to do with how the error is handled. If the DNS is down it can leave you hanging for an extended amount of time while the computer tries to "figure it out".

If the DNS is down, while the website is up, this is obviously a problem and the primary reason for wanting redundant DNS.

If the DNS is down while the site is also down this can leave your browser 'hanging' as opposed to just quickly letting you know the web site is down.

If the DNS is up, the browser will find (or not find) the web site situation much faster and return correct results that accurately (we hope) display either the site or the correct error.

Again, it's important for the hosts to acknowledge the registrar's requirements regardless of their reasons. There are a good number of International Registrars that require the DNS to be on separate networks and if the site owner cannot accomplish this then the domain cannot be hosted. For this market you'll want to do your best to comply.

Duhhh... I thought that the host for my website HAS to be the one providing my dns service. In fact, the means by which I activate a new domain is to go to my registrar and enter the host's nameservers for my domain.

Right??? Right??? You are perfectly able to handle your own DNS whether it be privately or via a third party as was suggested above. There are good and bad points to either option. On one hand you gain more control over the DNS, which can make moving the domain easier but on the other hand you are responsible for it which, if you're not 100% in the area can wreak havoc on the domain since the host or the third party may make a change while you were not looking that can result in leaving your DNS entries fubar until you fix them. By having the host handle your DNS you are also allowing them to be responsible for ensuring everything is working as it should be which for many is the wiser way to go. By the way, FQ now hosts one of my domains. Super great folks. Seeing Deb's post here was like -- I dunno -- a visit by the queen, maybe. LOL! I don't know about "queen" but rather another "WHT Addict"

Originally posted by bellgamin
...So how in the world could/would someone make use of a 3rd party for dns service?

By the way, FQ now hosts one of my domains. Super great folks. Seeing Deb's post here was like -- I dunno -- a visit by the queen, maybe.


We have web hosting customers that provide their own DNS. In that case, they could use a third party service if they wished. They just need to resolve the right names to the right IP addresses that we assign them.

You could also just list yourself as an alternate server and provide backup to your ISPs nameservers by using a third party domain name service.

Of course if your ISPs nameservers are down, there is a good chance that the web site and email will be unavailable as well.

But as to the original question in the subject of your post. I think that two are plenty for redundancy. Although you may need more for load balancing.

Originally posted by bellgamin
Under my present host I have 3 name servers.

In looking for a potential new host, I note that some have only 2 name servers. In fact, I may be wrong but I seem to remember one host that only had one.

Sheesh, I know I win the loving cup for dumb question of the month, but is there any significance to the number of nameservers???

Aloha from Hawaii,
bellgamin

I would not worry so much as to the number, provided you have two or more; you should be more concerned about having them on different networks. There are not very many moving parts in a DNS server, the network they are connected to is more likely to fail (well, the hardware too, but you didn't use ghetto sunmoonstar hardware did you?).

I think were missing the point. Redundant name servers are a must if you are working with mission critical sites. If you can afford for your site to go down then it isn't a problem but if one of your clients is going to call the lawyers when 15k/hr in business is going down the tubes because you hosted both name servers on the same machine then......I don't know what to tell you.

Yes you can do it but is it worth the liablility?

Though this is the case for few hosts now adays, your nameservers SHOULD be on different networks. Here's how you can check this:

1) Compare the IP addresses of the nameservers. Are they in the same class b (or even class c)? Here's the format:

classa.b.c.d

so...

192.168.1.100 (the .1 is the class c part, .168 is the class b part)

If they are in the same class c, then you have a problem. It's likely that they are on the same server, but are in the same data center and on the same network segment at the least.

2) traceroute to the name servers and observe the traces.

Originally posted by kwimberl
Though this is the case for few hosts now adays, your nameservers SHOULD be on different networks. Here's how you can check this:

1) Compare the IP addresses of the nameservers. Are they in the same class b (or even class c)? Here's the format:

classa.b.c.d

so...

192.168.1.100 (the .1 is the class c part, .168 is the class b part)

If they are in the same class c, then you have a problem. It's likely that they are on the same server, but are in the same data center and on the same network segment at the least.


Most of the Internet is now using CIDR where the networks are split with a netmask, and not by a class.