Direct DNS server connection

The interface directly measures DNS server response times for points with Location2 set to 10.

TCPResponse invokes the Windows API function DnsQuery() to connect to port 53 of the specified machine, for example, a machine specified using DEVICE=192.168.10.20 in the InstrumentTag. The interface uses the value of the keyword INPUT in the InstrumentTag, for example, INPUT =www.anothercompany.com as the first parameter to DnsQuery(). In other words, TCPResponse queries 192.168.10.20 for the IP address of www.anothercompany.com.

The response time measured by the interface is the amount of time it takes for the DnsQuery() function to complete. If the PI point is of type String, TCPResponse writes the value of the IP address translation; for example, 192.168.10.100. Otherwise, TCPResponse writes the response time value. If the response from DNS server does not indicate a Type A record, or if DnsQuery() fails, the interface writes the value Bad Input. If the interface does not receive a reply within a user-specified timeout duration, it writes I/O Timeout.