Nothing to worry about:
dig ntp1.dlink.com
; <<>> DiG 9.2.4 <<>> ntp1.dlink.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25900
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0
;; QUESTION SECTION:
;ntp1.dlink.com. IN A
;; ANSWER SECTION:
ntp1.dlink.com. 223 IN A 61.67.210.241
ntp1.dlink.com. 223 IN A 207.232.83.70
;; AUTHORITY SECTION:
dlink.com. 223 IN NS irvine.dlink.com.
dlink.com. 223 IN NS ns1.dlink.com.
Basically you can say there're two hosts running dlink ntp server