Starting the DNS server fails. restarting named shows the following error:

service named restart
Stopping named: [ OK ]
Starting named:
Error in named configuration:
zone 0.0.127.IN-ADDR.ARPA/IN: loaded serial 20010622
zone domain1.com/IN: loaded serial 1415397236
zone domain2.org/IN: loaded serial 1415411359
zone domain3.com/IN: loaded serial 1415556389

Thats the okay part
And then you see this:

zone domain4.com/IN: NS 'ns2.domain4.com' has no address records (A or AAAA)
zone domain4.com/IN: not loaded due to errors.

Resolution:

Add an A record for the nameserver ns2.domain4.com in the zone DNS manager in plesk. The restart named.

# service named restart