为什么即使用 flush dns 后还有残留？

win 7上，用了 runas /user:administrator 启动命令行
输入 ipconfig /flushdns ，然后 /displaydns看见下面的。由于字数限制，下面只是一部分。

为啥还有残留？怎么彻底清除？

Windows IP Configuration

dl-client958.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client958.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 50.16.187.233


dl-client958.dropbox.com
----------------------------------------
No records of type AAAA


158.225.21.23.in-addr.arpa
----------------------------------------
Record Name . . . . . : 158.225.21.23.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client939.dropbox.com


dl-client934.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client934.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.206.222


dl-client934.dropbox.com
----------------------------------------
No records of type AAAA


dl-client926.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client926.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.44.36


dl-client926.dropbox.com
----------------------------------------
No records of type AAAA


dl-client910.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client910.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.82.212


dl-client910.dropbox.com
----------------------------------------
No records of type AAAA


dl-client902.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client902.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.208.17


dl-client902.dropbox.com
----------------------------------------
No records of type AAAA


dl-client878.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client878.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.207.120


dl-client878.dropbox.com
----------------------------------------
No records of type AAAA


dl-client830.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client830.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.245.131


dl-client830.dropbox.com
----------------------------------------
No records of type AAAA


dl-client822.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client822.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.190.242


dl-client822.dropbox.com
----------------------------------------
No records of type AAAA


dl-client814.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client814.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.23.107.172


dl-client814.dropbox.com
----------------------------------------
No records of type AAAA


dl-client806.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client806.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . : Answer
A (Host) Record . . . : 23.23.107.117


dl-client806.dropbox.com
----------------------------------------
No records of type AAAA


48.130.101.75.in-addr.arpa
----------------------------------------
Record Name . . . . . : 48.130.101.75.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client642.dropbox.com


32.214.17.50.in-addr.arpa
----------------------------------------
Record Name . . . . . : 32.214.17.50.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client250.dropbox.com





Record Name . . . . . : 12.166.160.108.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : client37.dropbox.com


Record Name . . . . . : 12.166.160.108.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : client68.dropbox.com


202.111.23.23.in-addr.arpa
----------------------------------------
Record Name . . . . . : 202.111.23.23.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client914.dropbox.com


53.169.21.23.in-addr.arpa
----------------------------------------
Record Name . . . . . : 53.169.21.23.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client846.dropbox.com


28.124.23.23.in-addr.arpa
----------------------------------------
Record Name . . . . . : 28.124.23.23.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client629.dropbox.com


76.217.129.174.in-addr.arpa
----------------------------------------
Record Name . . . . . : 76.217.129.174.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client189.dropbox.com


80.208.16.50.in-addr.arpa
----------------------------------------
Record Name . . . . . : 80.208.16.50.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client95.dropbox.com


dl-debug36.dropbox.com
----------------------------------------
Record Name . . . . . : dl-debug36.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.20.249.207


dl-debug36.dropbox.com
----------------------------------------
No records of type AAAA


148.249.20.107.in-addr.arpa
----------------------------------------
Record Name . . . . . : 148.249.20.107.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-debug27.dropbox.com


dl-debug24.dropbox.com
----------------------------------------
Record Name . . . . . : dl-debug24.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.20.249.119


dl-debug24.dropbox.com
----------------------------------------
No records of type AAAA


dl-debug12.dropbox.com
----------------------------------------
Record Name . . . . . : dl-debug12.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.20.249.56


dl-debug12.dropbox.com
----------------------------------------
No records of type AAAA


dl-client775.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client775.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.22.234.83


dl-client775.dropbox.com
----------------------------------------
No records of type AAAA


dl-client767.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client767.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 174.129.193.117


dl-client767.dropbox.com
----------------------------------------
No records of type AAAA


dl-client751.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client751.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.22.238.106


dl-client751.dropbox.com
----------------------------------------
No records of type AAAA


dl-client743.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client743.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 50.17.226.173


dl-client743.dropbox.com
----------------------------------------
No records of type AAAA


dl-client719.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client719.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.21.116.50


dl-client719.dropbox.com
----------------------------------------
No records of type AAAA


dl-client671.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client671.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 50.17.217.94


dl-client671.dropbox.com
----------------------------------------
No records of type AAAA


dl-client663.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client663.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 50.16.231.91


dl-client663.dropbox.com
----------------------------------------
No records of type AAAA


dl-client655.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client655.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 107.21.108.33


dl-client655.dropbox.com
----------------------------------------
No records of type AAAA


dl-client647.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client647.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.48.22


dl-client647.dropbox.com
----------------------------------------
No records of type AAAA


dl-client639.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client639.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.175.206


dl-client639.dropbox.com
----------------------------------------
No records of type AAAA


dl-client559.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client559.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.23.226.202


dl-client559.dropbox.com
----------------------------------------
No records of type AAAA


dl-client535.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client535.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.23.223.77


dl-client535.dropbox.com
----------------------------------------
No records of type AAAA


138.222.23.23.in-addr.arpa
----------------------------------------
Record Name . . . . . : 138.222.23.23.in-addr.arpa.
Record Type . . . . . : 12
Time To Live . . . . : 86400
Data Length . . . . . : 8
Section . . . . . . . : Answer
PTR Record . . . . . : dl-client528.dropbox.com


dl-client527.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client527.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.23.223.48


dl-client527.dropbox.com
----------------------------------------
No records of type AAAA


dl-client511.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client511.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.23.217.150


dl-client511.dropbox.com
----------------------------------------
No records of type AAAA


dl-client503.dropbox.com
----------------------------------------
Record Name . . . . . : dl-client503.dropbox.com
Record Type . . . . . : 1
Time To Live . . . . : 86400
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 23.21.220.167


dl-client503.dropbox.com
----------------------------------------
No records of type AAAA