ft.nai.com and bad SOA

[Gary Bennett]

The current SOA for the McAfee ftp site, ftp.nai.com, is
daldc3dns.na.nai.com, which does not resolve to any IP address. 
Periodically, the resolution of ftp.nai.com fails w/this dig result:
 
; <<>> DiG 9.2.2 <<>> @name.ufl.edu ftp.nai.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11191
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
 
;; QUESTION SECTION:
;ftp.nai.com.                   IN      A
 
;; AUTHORITY SECTION:
ftp.nai.com.            5865    IN      SOA     daldc3dns.na.nai.com.
hostmaster.daldc3dns.na.nai.com. 2006032415 28800 7200 604800 86400
 
;; Query time: 1 msec
;; SERVER: 128.227.128.24#53(name.ufl.edu)
;; WHEN: Mon Jun 19 08:22:31 2006
;; MSG SIZE  rcvd: 89
 
    
     After flushing the cache, dig returns:
 
; <<>> DiG 9.2.2 <<>> ftp.nai.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27866
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
 
;; QUESTION SECTION:
;ftp.nai.com.                   IN      A
 
;; ANSWER SECTION:
ftp.nai.com.            29      IN      A       216.143.70.11
 
;; AUTHORITY SECTION:
ftp.nai.com.            82477   IN      NS      snc3dns.nai.com.
ftp.nai.com.            82477   IN      NS      dal3dns.nai.com.
 
;; Query time: 1 msec
;; SERVER: 159.178.61.125#53(159.178.61.125)
;; WHEN: Mon Jun 19 08:24:22 2006
;; MSG SIZE  rcvd: 89
 
I understand the SOA problem w/the vendor, but the resolver behavior
still confuses me.  Why does it fail, but correct itself after flushing
the cache?  TIA for any suggestions or information.  Thanks.
 
 
gary