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1.0 Network Infrastructure and Connectivity

Network Fundamentals Practice Questions

Devices, interfaces, OSI/TCP-IP layers, IPv4 headers, and packet forwarding.

Author-reviewed by LabFabric · 6 September 2026 · Report a content issue

One solved question, so you can see how these are marked

Which device primarily forwards Ethernet frames within a LAN by consulting a MAC address table?

Layer 2 switch

A Layer 2 switch learns source MAC addresses and forwards frames based on its MAC address table within a broadcast domain.

Every question in the set below is marked like this. The answers stay hidden until you pick one.

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All 14 Network Fundamentals questions in this set

Answers and explanations appear when you work through the set above.

  1. What is a router's core forwarding decision for an IPv4 packet?

    • Choose the best matching route for the destination IP address
    • Choose the source MAC address
    • Assign a TCP port
    • Resolve every hostname with DNS

  2. At which OSI layer do IPv4 and IPv6 operate?

    • Network
    • Data Link
    • Transport
    • Session

  3. Which TCP/IP model layer most closely combines the OSI physical and data-link layers?

    • Network access
    • Internet
    • Transport
    • Application

  4. A host sends traffic to a destination outside its local subnet. To whose MAC address does it normally build the first Ethernet frame?

    • Its default gateway
    • The final remote host
    • The DNS server
    • The source host

  5. What does ARP resolve on an IPv4 Ethernet LAN?

    • An IPv4 address to a MAC address
    • A hostname to an IPv4 address
    • A VLAN ID to a subnet mask
    • A TCP port to an application

  6. Which address is rewritten at every routed Ethernet hop while the end-to-end IPv4 source and destination usually remain unchanged?

    • The Ethernet source and destination MAC addresses
    • The IPv4 destination address
    • The TCP destination port
    • The application payload

  7. What is the purpose of the TTL field in an IPv4 header?

    • Limit packet lifetime and prevent persistent routing loops
    • Encrypt the packet
    • Identify the TCP application
    • Select a VLAN

  8. Which IPv4 header field lets a receiver reassemble fragments from the same original packet?

    • Identification
    • DSCP
    • Header checksum
    • Protocol

  9. What does the protocol field in an IPv4 header identify?

    • The payload's next-layer protocol, such as TCP or UDP
    • The switchport speed
    • The destination VLAN
    • The default gateway

  10. Why is full-duplex Ethernet preferable to half-duplex Ethernet on a point-to-point switch link?

    • Both ends can transmit and receive simultaneously without collisions
    • It doubles the IPv4 address space
    • It removes the need for MAC addresses
    • It makes STP unnecessary

  11. What does a switch do when it receives a unicast frame for a destination MAC address that is absent from its MAC table?

    • Floods it out eligible ports in the VLAN
    • Drops it immediately
    • Routes it to the default gateway
    • Changes the frame's destination MAC

  12. Which cable type is typically used to connect a PC or router Ethernet interface to a switch port?

    • Straight-through Ethernet cable
    • Rollover console cable
    • Serial DCE cable
    • Fibre crossover cable only

  13. Which command is most useful for quickly verifying interface IP addresses and line/protocol status on Cisco IOS?

    • show ip interface brief
    • show mac address-table
    • show access-lists
    • show version | include license

  14. Which statement best describes encapsulation?

    • Protocols add headers or trailers as data moves down the stack
    • A switch removes all headers before forwarding
    • A router converts every packet into a TCP segment
    • DNS replaces IP addressing