The SetKeepAliveTime method is used to set how often TCP attempts to verify that an idle connection is still available by ...

The SetKeepAliveTime method is used to set how often TCP attempts to verify that an idle connection is still available by sending a Keep Alive packet. If the remote system is still reachable and functioning, it will acknowledge the Keep Alive transmission. Keep Alive packets are not sent by default. This feature may be enabled in a connection by an application. The method returns an integer value that can be interpretted as follows: 
0 - Successful completion, no reboot required
1 - Successful completion, reboot required
64 - Method not supported on this platform
65 - Unknown failure
66 - Invalid subnet mask
67 - An error occurred while processing an Instance that was returned
68 - Invalid input parameter
69 - More than 5 gateways specified
70 - Invalid IP  address
71 - Invalid gateway IP address
72 - An error occurred while accessing the Registry for the requested information
73 - Invalid domain name
74 - Invalid host name
75 - No primary/secondary WINS server defined
76 - Invalid file
77 - Invalid system path
78 - File copy failed
79 - Invalid security parameter
80 - Unable to configure TCP/IP service
81 - Unable to configure DHCP service
82 - Unable to renew DHCP lease
83 - Unable to release DHCP lease
84 - IP not enabled on adapter
85 - IPX not enabled on adapter
86 - Frame/network number bounds error
87 - Invalid frame type
88 - Invalid network number
89 - Duplicate network number
90 - Parameter out of bounds
91 - Access denied
92 - Out of memory
93 - Already exists
94 - Path, file or object not found
95 - Unable to notify service
96 - Unable to notify DNS service
97 - Interface not configurable
98 - Not all DHCP leases could be released/renewed
100 - DHCP not enabled on adapter
Other - For integer values other than those listed above, refer to Win32 error code documentation.