Proper way of setting up one DNS server for multiple domains

domain-name-system

I have a dillema about what would be the proper way to setup one DNS as master server for two or more domains? For example, if I have two domains: first.com and second.com, and one DNS server with public IP address.
Should I setup in this manner:

zone file for first.com

$ORIGIN first.com.
@       IN     SOA   ns1.first.com. hostmaster.first.com. (
               2003080800 ; serial number
               3h         ; refresh =  3 hours 
               15M        ; update retry = 15 minutes
               3W12h      ; expiry = 3 weeks + 12 hours
               2h20M      ; minimum = 2 hours + 20 minutes
               )
              IN      NS     ns1.first.
              IN      NS     ns2.first.

ns1           IN      A      70.0.0.3 # address for example purposes
ns2           IN      A      70.0.0.4 #

zone file for second.com:

$ORIGIN second.com.
@       IN     SOA   ns1.second.com. hostmaster.second.com. (
               2003080800 ; serial number
               3h         ; refresh =  3 hours 
               15M        ; update retry = 15 minutes
               3W12h      ; expiry = 3 weeks + 12 hours
               2h20M      ; minimum = 2 hours + 20 minutes
               )
              IN      NS     ns1.second.
              IN      NS     ns2.second.

ns1           IN      A      70.0.0.3 # address for example purposes
ns2           IN      A      70.0.0.4 #

and in the parent zone create four NS records and four glue A records:

first         IN      NS     ns1.first.com.
              IN      NS     ns2.first.com.

second        IN      NS     ns1.second.com.
              IN      NS     ns2.second.com.

ns1.first     IN      A      70.0.0.3
ns2.first     IN      A      70.0.0.4

ns1.second    IN      A      70.0.0.3
ns2.second    IN      A      70.0.0.4

Or should it be configured so that in second.com we define ns1.first. as master name server, and two NS records for ns1.first.com. and ns2.first.com. without A records for those? Like this:

$ORIGIN second.com.
@       IN     SOA   ns1.first.com. hostmaster.second.com. (
                   2003080800 ; serial number
                   3h         ; refresh =  3 hours 
                   15M        ; update retry = 15 minutes
                   3W12h      ; expiry = 3 weeks + 12 hours
                   2h20M      ; minimum = 2 hours + 20 minutes
                   )
                  IN      NS     ns1.first.
                  IN      NS     ns2.first.

In that case, in parent zone we would define four NS records and two A glue records:

first         IN      NS     ns1.first.com.
              IN      NS     ns2.first.com.

second        IN      NS     ns1.first.com.
              IN      NS     ns2.first.com.

ns1.first     IN      A      70.0.0.3
ns2.first     IN      A      70.0.0.4

ns2 is the name server configured as slave server for both domains, also with public IP address.

My appologies if question is trivial, but after reading substantial amount of text and thinking about it I'm still not sure about what is correct way of doing this.

Thanks

Best Answer

I think that typically as a nameserver operator you would want to decide once and for all what the names of your nameservers are and then use those names for any number of zones that you host.

Your nameservers could be named something customer/purpose neutral like ns1.hostingcompany.example, ns2.hostingcompany.example, ns3.hostingcompany.example, ns4.hostingcompany.example.

It is possible to refer to the same nameservers by multiple names, but that will tend to result in glue records for many domains (maybe outside of your control?), effectively making it harder for you to maintain your own environment.

Related Topic