When this would happen ?

[Scottie Lu]

Dear Sir :

        The following data is what confuses me!!

; <<>> DiG 8.3 <<>> @dns.hinet.net www.istudy.com.tw.
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
            ^^^^^^^^
;; QUERY SECTION:
;;      www.istudy.com.tw, type = A, class = IN

;; ANSWER SECTION:
www.istudy.com.tw.      1D IN A         61.222.96.52
                                        ^^^^

;; AUTHORITY SECTION:
istudy.com.tw.          1D IN NS        www.istudy.com.tw.
istudy.com.tw.          1D IN NS        istudy.com.tw.

;; ADDITIONAL SECTION:
www.istudy.com.tw.      1D IN A         61.222.96.52
istudy.com.tw.          1D IN A         61.222.96.52


why does A record of www.istudy.com.tw always have 1D TTL ?
why doesn't it countdown sec by sec ?
ps: The name server I queried is not authoritive for this domain 

Best Regard,
Scottie

2002/12/10