Only a subset of A records for a domain name returned

When I query the authoritative DNS servers for a domain, I get
the following:

dig @ns21.yahoo.com proxy-kk-west.idp.inktomisearch.com

; <<>> DiG 9.2.2 <<>> @ns21.yahoo.com
proxy-kk-west.idp.inktomisearch.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56036
;; flags: qr aa rd; QUERY: 1, ANSWER: 24, AUTHORITY: 2, ADDITIONAL: 1

;; QUESTION SECTION:
;proxy-kk-west.idp.inktomisearch.com. IN A

;; ANSWER SECTION:
proxy-kk-west.idp.inktomisearch.com. 300 IN CNAME
idpproxy-kkw1.idp.inktomisearch.com.
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.150
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.128
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.129
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.130
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.131
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.132
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.133
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.134
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.135
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.136
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.137
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.138
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.139
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.140
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.141
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.142
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.143
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.144
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.145
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.146
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.147
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.148
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.149

;; AUTHORITY SECTION:
idp.inktomisearch.com. 300 IN NS ns21.yahoo.com.
idp.inktomisearch.com. 300 IN NS ns22.yahoo.com.

;; ADDITIONAL SECTION:
ns21.yahoo.com. 1408 IN A 66.163.169.46

;; Query time: 71 msec
;; SERVER: 66.163.169.46#53(ns21.yahoo.com)
;; WHEN: Mon Mar 21 21:03:52 2005
;; MSG SIZE rcvd: 509

But when I query my ISP's DNS server, I only get a subset of
these records returned:

dig proxy-kk-west.idp.inktomisearch.com
; <<>> DiG 9.2.2 <<>> proxy-kk-west.idp.inktomisearch.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53749
;; flags: qr rd ra; QUERY: 1, ANSWER: 13, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;proxy-kk-west.idp.inktomisearch.com. IN A

;; ANSWER SECTION:
proxy-kk-west.idp.inktomisearch.com. 300 IN CNAME
idpproxy-kkw1.idp.inktomisearch.com.
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.128
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.129
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.130
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.131
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.132
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.133
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.134
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.135
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.136
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.137
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.138
idpproxy-kkw1.idp.inktomisearch.com. 300 IN A 66.196.78.139

;; AUTHORITY SECTION:
idp.inktomisearch.com. 300 IN NS ns22.yahoo.com.
idp.inktomisearch.com. 300 IN NS ns21.yahoo.com.

;; ADDITIONAL SECTION:
ns21.yahoo.com. 1634 IN A 66.163.169.46
ns22.yahoo.com. 1152 IN A 216.109.116.23

;; Query time: 105 msec
;; SERVER: 206.13.29.12#53(206.13.29.12)
;; WHEN: Mon Mar 21 21:06:15 2005
;; MSG SIZE rcvd: 349

So there are 23 A records in the reply from Yahoo's DNS server, but
only
a dozen from my ISP's DNS server (sbcglobal.net). The TTL associated
with the
records seems fairly short (300). I can replicate this problem using
other
DNS servers (for the same lookup) as well.

Can someone shed some light on these results? Thanks ...

Richard