CCNA

CCNA

1. OSI model

   • Layer 1: Physical
     • Voltage levels
     • Physical data rates
     • Physical connectors
   • Layer 2: Data Link
     • Makes sure data is formatted correctly
     • Error correction
     • Makes sure data is delivered reliably
     • Ethernet
   • Layer 3: Network
     • Connectivity and path selection
     • IPV4 & IPV6
   • Layer 4: Transport
     • TCP
       • Reliable
     • UDP
       • Unreliable
   • Layer 5: Session
     • Takes care of estasblishing, managing, and terminating sessions.
   • Layer 6: Presentation
     • Formats and structures data
     • Ensures data is readable by the application layer
   • Layer 7: Application
     • HTTP, FTP, ETC
   • PDU
     • Protocol Data Unit
     • Transport
       • Segment
     • Network
       • Packet
     • Data Link Layer
       • Frame

2. TCP/IP Stack

   • Application
   • Transport
   • Internet
   • Network access