This read-only 64-bit counter tracks the total number of bytes received, inbound, by the host identified by this row. Separating inbound from total bytes lets admins distinguish hosts that are mainly downloading or receiving data from those primarily sending, useful for spotting asymmetric traffic patterns like large downloads or DDoS backscatter. A host with unusually high ntqInBytes relative to ntqOutBytes might simply be downloading a large update, or could indicate it's the target of an inbound flood.