Thanks for your reply, I should have include the SOA record before so my question would be clearer, it's below. The last entry is the NS 'A' record and that's what I'd like to know if it is needed.
Thanks again.
1 $TTL 1D
2 mydomain.com. IN SOA mydomain.com. postmaster.mydomain.COM. (
3 2009061202 ;Serial number
4 3600 ;Refresh
5 1800 ;Retry
6 604800 ;Expire
7 86400 ) ;Minimum
8 ;
9 mydomain.com. IN NS ns1.mydomain.com.
10 mydomain.com. IN NS ns1.secondarydns.com.
11 ;
12 mydomain.com. IN MX 1 mail.mydomain.com.
13 ;
14 mydomain.com. IN A 192.168.1.62
15 mail.mydomain.com. IN A 192.168.1.62
16 ftp.mydomain.com. IN A 192.168.1.62
17
www.mydomain.com. IN A 192.168.1.62
18 ns1.mydomain.com. IN A 192.168.1.62