Inconsistency in Relational Databases

I generally get confused when the term consistency is used. NoSQL tutorials always refer to the reads whereas Relational tutorials refer to a consistent state (ensuring referential integrity constraint) When the data is distributed across multiple servers (ex 1 master- n slaves configuration) 1. Do relational databases ensure consistency in reads? I mean a committed write is immediately available to be read by other transactions? I suspect not given network is involved, making Relational DBs as eventual consistent DBs. 2. Do relational databases ensure referential integrity constraint well?