SQL Server 2008 R2 linkedServer to Oracle 12c

Second thing is that we observed that ping from sql server to oracle 12c database is giving sometime request time out. SQL Server 2008 R2 with SP3 on Windows Server 2008 R2,Oracle Database 12c (12.1.0.1) on IBM AIX 6.1 TL9,Oracle Driver version (12.2) ,. What was the reason behind this ?

Windows 2008 VPS via SQL Server 2008 R2 linkedServer to Oracle 12c.