There is a good descrition of the network layer and TCP in the related link.
NO. In general TCP and UDP are transport protocols that operates in Layer 4 Transport Layer
TCP and UDP are transport layer protocols; the OSI layer is layer 4 (transport)
TCP is the protocol of network layer, It is connection oriented protocol. UDP is the protocol of network layer, It is connection less protocol.
The Transport layer
Network Interface Layer
With regard to the TCP/IP Network Model, the network access Layer is the lowest logical layer in the model and provides specifications for how data (bits) should move over the network.
signaling
TCP
What is the purpose of the TCP/IP Network Access layer
Network
The data-link layer The physical layer
Controls the hardware devices and media that make up the network
Tcp/ip