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Author: Tianle Yuan

** 👨‍💻 Networking**⚓︎

Interview Questions for Networking

Overview⚓︎

Here is the table of the 7 layers:

|Nums|Layers |Data Units| |Functions |
|:-:|:-:|:-:|:-:| |7|Application Layer |Data |Mail Services,Directory Services,FTAM | |6|Presentation Layer |Data |Encryption/Decryption, Compression| |5|Session Layer |Data |Session Establishment, Synchronization,Dialog Controller| |4|Transport Layer |Segments,Datagram |Segmentation| |3|Network Layer |Packets |Traffic control,Fragmentation,Routing| |2|Data Link Layer |Frames |Flow control,Error control,Access control| |1|Physical Layer |Bits |Bit Synchronization,Bit rate control,Physical Topologies|

For the seven layers, here are some corresponding protocols and devices/apps:

  • Protocol:

    • Ethernet (IEEE 802.3)
    • Wi-Fi (IEEE 802.11)
    • Bluetooth
    • DSL (Digital Subscriber Line)
    • USB (Universal Serial Bus)
    • RS-232
  • Devices:

    • Hubs
    • Repeaters
    • Cables (e.g., twisted pair, coaxial, fiber optic)
    • Network Interface Cards (NICs)
    • Wireless Access Points

=== "2. Dlk Lr"

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    - Protocol:

        - Ethernet (IEEE 802.3)
        - Wi-Fi (IEEE 802.11)
        - PPP (Point-to-Point Protocol)
        - HDLC (High-Level Data Link Control)
        - Frame Relay
        - ATM (Asynchronous Transfer Mode)

    - Devices:

        - Switches
        - Bridges
        - Wireless Access Points
        - Network Interface Cards (NICs)
        - Protocol Analyzers (e.g., Wireshark)

=== "3. Ntw Lr"

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    - Protocol:

        - IPv4 (Internet Protocol version 4)
        - IPv6 (Internet Protocol version 6)
        - ICMP (Internet Control Message Protocol)
        - IGMP (Internet Group Management Protocol)
        - OSPF (Open Shortest Path First)
        - RIP (Routing Information Protocol)
        - BGP (Border Gateway Protocol)

    - Devices:

        - Routers
        - Layer 3 Switches
        - Firewalls
        - Applications:
        - Routing software (e.g., Cisco IOS, Juniper Junos OS)
        - Network management and monitoring tools (e.g., SolarWinds Network Performance Monitor)

=== "4. Tsp Lr"

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    - Protocol:

        - TCP (Transmission Control Protocol)
        - UDP (User Datagram Protocol)
        - SCTP (Stream Control Transmission Protocol)
        - DCCP (Datagram Congestion Control Protocol)


    - Applications:

        - Wireshark (for analyzing TCP/UDP packets)
        - Netstat (for monitoring active network connections)

=== "5. Ssn Lr"

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    - Protocol:

        - TLS (Transport Layer Security)
        - SSL (Secure Sockets Layer)
        - SSH (Secure Shell)
        - L2TP (Layer 2 Tunneling Protocol)
        - PPTP (Point-to-Point Tunneling Protocol)

    - Applications:

        - VPN clients and servers (e.g., OpenVPN, Cisco AnyConnect)
        - Remote desktop tools (e.g., TeamViewer, Microsoft Remote Desktop)
        - Network file sharing systems (e.g., SMB, NFS)

=== "6. Pst Lr"

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    - Protocol:

        - MIME (Multipurpose Internet Mail Extensions)
        - XDR (External Data Representation)
        - ASN.1 (Abstract Syntax Notation One)
        - SSL/TLS (Secure Sockets Layer / Transport Layer Security)
        - JSON (JavaScript Object Notation)
        - XML (eXtensible Markup Language)

    - Applications:

        - Encryption/decryption tools (e.g., OpenSSL)
        - Data compression software (e.g., gzip, WinZip, WinRAR)
        - Web browsers (for rendering MIME types, e.g., Chrome, Firefox, Safari)

=== "7. Apl Lr"

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    - Protocol:

        - HTTP (Hypertext Transfer Protocol)
        - HTTPS (Hypertext Transfer Protocol Secure)
        - FTP (File Transfer Protocol)
        - TFTP (Trivial File Transfer Protocol)
        - SMTP (Simple Mail Transfer Protocol)
        - POP3 (Post Office Protocol version 3)
        - IMAP (Internet Message Access Protocol)
        - DNS (Domain Name System)
        - SNMP (Simple Network Management Protocol)
        - Telnet
        - DHCP (Dynamic Host Configuration Protocol)
        - LDAP (Lightweight Directory Access Protocol)
        - SIP (Session Initiation Protocol)
        - XMPP (Extensible Messaging and Presence Protocol)

    - Applications:

        - Web browsers (e.g., Chrome, Firefox, Safari)
        - Email clients (e.g., Microsoft Outlook, Mozilla Thunderbird, Apple Mail)
        - File transfer clients (e.g., FileZilla, WinSCP)
        - Instant messaging apps (e.g., WhatsApp, Telegram, Signal)
        - Voice and video communication software (e.g., Zoom, Microsoft Teams, Skype)
        - Network management and monitoring tools (e.g., SolarWinds Network Performance Monitor, Nagios)

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