Help me out I dn't know C#

HI,

    I am getting the following exception is my log file, can any one help me in indentifying the issue?? Is it network issue? or any suggestion , how to proceed 

My C# code is trying to ping  different severs for information. But getting the following exception.

Server Pingable ==> XYZ
Exception in getting printer details  Object reference not set to an instance of an object.
Exception in connectToServer System.Net.NetworkInformation.PingException: An exception occurred during a Ping request. ---> System.Net.Sockets.SocketException: No such host is known
   at System.Net.Dns.GetAddrInfo(String name)
   at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6)
   at System.Net.Dns.GetHostAddresses(String hostNameOrAddress)
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress, Int32 timeout, Byte[] buffer, PingOptions options)
   --- End of inner exception stack trace ---
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress, Int32 timeout, Byte[] buffer, PingOptions options)
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress)
   at Connect.connectToServer(String ServerName)
Exception in connectToServer System.Net.NetworkInformation.PingException: An exception occurred during a Ping request. ---> System.Net.Sockets.SocketException: No such host is known
   at System.Net.Dns.GetAddrInfo(String name)
   at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6)
   at System.Net.Dns.GetHostAddresses(String hostNameOrAddress)
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress, Int32 timeout, Byte[] buffer, PingOptions options)
   --- End of inner exception stack trace ---
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress, Int32 timeout, Byte[] buffer, PingOptions options)
   at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress)
   at Connect.connectToServer(String ServerName)
Exception in connectToServer System.Net.NetworkInformation.PingException: An except