% APNIC found the following authoritative answer from: whois.apnic.net

% [whois.apnic.net]
% Whois data copyright terms    http://www.apnic.net/db/dbcopyright.html

% Information related to '2403:6000::/32'

% Abuse contact for '2403:6000::/32' is 'hm-changed@vnnic.vn'

inet6num:       2403:6000::/32
netname:        QTSC-VN
descr:          Quang Trung Software City Development Company
descr:          97-101 Nguyen Cong Tru Street, Saigon Ward, Ho Chi Minh City
country:        VN
admin-c:        THN10-AP
tech-c:         NTS12-AP
remarks:        For spamming matters, mail to abuse@qtsc.com.vn
status:         ALLOCATED PORTABLE
mnt-by:         MAINT-VN-VNNIC
mnt-lower:      MAINT-VN-QTSC
mnt-routes:     MAINT-VN-QTSC
mnt-irt:        IRT-VNNIC-AP
last-modified:  2025-12-16T04:03:09Z
source:         APNIC

irt:            IRT-VNNIC-AP
address:        Ha Noi, VietNam
phone:          +84-24-35564944
fax-no:         +84-24-37821462
e-mail:         hm-changed@vnnic.vn
abuse-mailbox:  hm-changed@vnnic.vn
admin-c:        NTTT1-AP
tech-c:         NTTT1-AP
auth:           # Filtered
mnt-by:         MAINT-VN-VNNIC
last-modified:  2026-04-21T02:07:47Z
source:         APNIC

person:         Nguyen Thanh Son
address:        QTSC-VN
country:        VN
phone:          +84-2837155985
e-mail:         thanhson@qtsc.com.vn
nic-hdl:        NTS12-AP
mnt-by:         MAINT-VN-VNNIC
last-modified:  2025-12-16T03:56:38Z
source:         APNIC

person:         Tran Hoang Nam
address:        QTSC-VN
country:        VN
phone:          +84-2837155985
e-mail:         nam@qtsc.com.vn
nic-hdl:        THN10-AP
mnt-by:         MAINT-VN-VNNIC
last-modified:  2025-12-16T03:56:01Z
source:         APNIC

% Information related to '2403:6000::/32AS24085'

route6:         2403:6000::/32
descr:          QTSC-VN
origin:         AS24085
mnt-by:         MAINT-VN-QTSC
last-modified:  2023-03-29T02:24:21Z
source:         APNIC

% This query was served by the APNIC Whois Service version 1.88.48 (WHOIS-AU5)