Some network traffic occurs simply because the network is active. For example, some network traffic occurs as a result of periodic retransmission of packets as "keepalive" requests, browser requests, polling, and the acknowledgment packets sent for each of these requests.

The following table documents packet types and their default send intervals.

Packet Type    Protocol   Transport           Interval
-----------    --------   ---------           --------
NetLogon       SMB        TCP/IP & NetBEUI    300 seconds
Browse         SMB        TCP/IP & NetBEUI    300 seconds (Windows NT 3.1)
                                              720 seconds (Windows NT 3.5x)
KeepAlive      NetBIOS    TCP/IP               60 minutes (Windows NT 3.5x)
SessionAlive   NetBIOS    NetBEUI              30 seconds (LAN Manager)
Poll/Final     LLC        NetBEUI              30 seconds (or ACK to Poll)
KeepAlive      NetBIOS    IPX                  30 seconds
Echo SMB       SMB        Direct Host IPX     240 seconds
				

NOTE: The Browse packet type mentioned above indicates network traffic between a Windows NT primary domain controller (PDC) and its backup domain controllers (BDCs).

The Windows NT redirector echoes an SMB every 30 seconds to each server that has an associated Long Term Request outstanding.

Some of the default values can be adjusted by changing the appropriate values in the Windows NT registry. For more information about these settings, query on the following words in the Microsoft Knowledge Base:

For additional information on adjusting PDC browse broadcasts, please see the following article in the Microsoft Knowledge Base: