When I access submain made by cpanel,
show message &unknown host(ping). please check dns.(broweser)&

I access it into web.

Is it fix my problem?

test subdomain : ping exit.getplex.com

C:\WINDOWS&ping exit.getplex.com
Unknown host exit.getplex.com.

C:\WINDOWS&ping getplex.com

Pinging getplex.com [211.172.232.128] with 32 bytes of data:

Reply from 211.172.232.128: bytes=32 time=9ms TTL=248
Reply from 211.172.232.128: bytes=32 time=8ms TTL=248
Reply from 211.172.232.128: bytes=32 time=8ms TTL=248
Reply from 211.172.232.128: bytes=32 time=7ms TTL=248

Ping statistics for 211.172.232.128:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 7ms, Maximum = 9ms, Average = 8ms