QUESTIONS AND VERIFIED ANSWERS 2024
Application
Function: Application software, network applications.
Anything you can see with your eyeballs like
web browsers and email.
Presentation
Function: Data conversion utilities. Protocol
Conversion, data translation. Data
encryption/decryption.
Session
Function: Network Operating System. Establishes,
manages & terminates sessions
Transport
Function: Network Operating System. Ensures Error
Free Packets
Network
Function: Router, Layer 3 switches. Provides routing
decisions. NAT, PAT
Data Link
Function: Switches, NIC, Token Ring, Frame Relay,
Bridge. Provides for flow of data. NIC
FUNCTIONS at this layer. Bits pass over
physical layer between devices on a LAN
(collision domain)
Physical
, Function: 802.11, Repeater, Modem, Bluetooth,
Ethernet, hubs, Network Cabling, Wi-Fi.
Signals & Media
Application
Protocol: HTTP, FTP, SMIP, IMAP, SMTP
Presentation
Protocol: SSL, ASCII, JPEG, MIDI, MPEG, GIF,
MP3, MP4
Session
Protocol: NFS, SQL, PPTP, NetBIOS, PAP, SCP
(tunneling)
Transportation
Protocol: TCP (segments so no missing
packets), UDP (datagrams for
streaming like games), SCTP
Network
Protocol: IP, IPX, IPSec, RIP, IPv4, IPv6, ICMP
Data Link
Protocol: MAC addresses, ARP, PPP, HDLC,
LLC
Communication at MAC-address
level - forwards packets on Layer 2
devices, like a bridge.
Physical
Protocol: DSL, ISDN, physical NICs, twisted
pair cable, fiber. Questions about
"medium" refer to cabling.
TCP/IP
Transmission Control Protocol/Internet Protocol
OSI
Open System Interconnection