MCQs on Ethernet and Switching Concepts | CCNA Certification MCQs
Ethernet and Switching Concepts are fundamental to understanding network communications. This set of 40 multiple-choice questions (MCQs) covers key topics such as Ethernet frame structure, switching basics, VLANs, and Spanning Tree Protocol (STP), designed to help with certification exams.
1. Ethernet Frame Structure
- What is the size of the Ethernet frame header?
a) 12 bytes
b) 14 bytes
c) 18 bytes
d) 20 bytes - The Ethernet frame includes which of the following?
a) Destination MAC address
b) Payload data
c) FCS (Frame Check Sequence)
d) All of the above - What is the purpose of the FCS (Frame Check Sequence) in an Ethernet frame?
a) To identify the source MAC address
b) To ensure the integrity of the frame
c) To add the destination IP address
d) To set the maximum transmission speed - In an Ethernet frame, what does the EtherType field specify?
a) The source IP address
b) The destination MAC address
c) The type of protocol encapsulated in the frame
d) The speed of the network - What is the minimum size of an Ethernet frame?
a) 32 bytes
b) 48 bytes
c) 64 bytes
d) 128 bytes
2. Switching Basics
- Which layer of the OSI model is responsible for Ethernet switching?
a) Physical Layer
b) Data Link Layer
c) Network Layer
d) Transport Layer - A switch operates primarily at which layer of the OSI model?
a) Layer 1 (Physical)
b) Layer 2 (Data Link)
c) Layer 3 (Network)
d) Layer 4 (Transport) - How does a switch forward Ethernet frames?
a) Based on the source IP address
b) Based on the destination MAC address
c) Based on the source MAC address
d) Based on the Ethernet Type - Which of the following is true regarding switching?
a) Switches use flooding when they do not know the destination MAC address
b) Switches forward frames based on IP addresses
c) Switches increase network collisions
d) Switches operate at Layer 3 - Which type of switching method is commonly used by Layer 2 switches?
a) Store-and-forward
b) Cut-through
c) Fragment-free
d) All of the above
3. MAC Addresses and Frame Forwarding
- Which of the following is a MAC address format?
a) 192.168.1.1
b) 00:1A:2B:3C:4D:5E
c) 10.0.0.1
d) F0:12:34:56:78:90 - How does a switch learn the MAC addresses of devices on the network?
a) Through ARP requests
b) By listening to incoming frames and recording source MAC addresses
c) By broadcasting every frame
d) By sending out periodic ICMP Echo requests - When a switch receives a frame with an unknown destination MAC address, what does it do?
a) Drops the frame
b) Broadcasts the frame to all ports
c) Forward it to the default gateway
d) Sends the frame back to the source device - Which of the following is the correct format for a multicast MAC address?
a) 01:00:5E:xx:xx:xx
b) 00:00:00:00:00:00
c) FF:FF:FF:FF:FF:FF
d) 80:00:00:00:00:00 - What does the forwarding database (FDB) in a switch contain?
a) The IP addresses of devices
b) The MAC addresses and associated ports
c) The IP subnet masks
d) The routing table entries
4. VLANs (Virtual Local Area Networks)
- What is the purpose of a VLAN?
a) To segment traffic based on logical groups
b) To increase the speed of the network
c) To reduce broadcast traffic on the network
d) Both a and c - What is the range of VLAN IDs in IEEE 802.1Q?
a) 1–512
b) 1–1024
c) 1–4095
d) 1–65535 - Which of the following statements is true about VLAN 1?
a) It is the default VLAN for most switches
b) It is the reserved VLAN for system use only
c) It cannot be deleted
d) It is used exclusively for management traffic - What is the function of a trunk link between two switches?
a) To carry traffic for multiple VLANs
b) To carry traffic for only one VLAN
c) To prevent broadcast traffic
d) To limit the amount of VLANs on the network - Which protocol is used to tag frames in a VLAN trunk?
a) PPPoE
b) HTTP
c) IEEE 802.1Q
d) MPLS
5. Switch Operation and Configuration
- What is the role of the spanning tree algorithm (STA) in a network?
a) To prevent broadcast storms
b) To avoid routing loops
c) To provide fault tolerance
d) All of the above - What does the STP use to determine the best path in a network?
a) VLAN ID
b) MAC address
c) Root bridge and port roles
d) IP address - Which of the following is true about switch configuration?
a) Switch configuration is done only through CLI
b) Switches can be configured using a graphical user interface
c) Switch configuration is done through the browser only
d) Switch configuration requires a specialized tool - Which command is used to configure a VLAN on a Cisco switch?
a)vlan create
b)vlan add
c)vlan configuration
d)vlan database - How is the default VLAN on a switch typically configured?
a) VLAN 0
b) VLAN 1
c) VLAN 100
d) VLAN 50
6. Static VLANs, Dynamic VLANs, and VLAN Trunking
- Which of the following describes a static VLAN?
a) VLAN assignments are dynamically based on port membership
b) VLANs are manually configured on specific switch ports
c) VLANs are automatically assigned based on device type
d) VLANs are assigned using a DHCP server - What is the key characteristic of a dynamic VLAN?
a) It is configured manually on each switch port
b) It uses a VLAN management protocol to assign VLANs based on the MAC address
c) It is always used for VoIP traffic
d) It requires a separate VLAN ID for each port - VLAN Trunking allows multiple VLANs to travel across a single link between switches. Which of the following must be enabled for trunking?
a) IEEE 802.1X
b) IEEE 802.1Q
c) VTP (VLAN Trunking Protocol)
d) STP (Spanning Tree Protocol) - Which of the following is the default VLAN trunking protocol on most modern switches?
a) ISL (Inter-Switch Link)
b) 802.1Q
c) 802.3af
d) VTP - What is the default mode for VLAN trunking on a Cisco switch?
a) Dynamic Auto
b) Access
c) Trunk
d) Dynamic Desirable
7. STP (Spanning Tree Protocol)
- Which version of STP is considered the standard in modern Ethernet networks?
a) RSTP (Rapid Spanning Tree Protocol)
b) PVST+ (Per VLAN Spanning Tree Plus)
c) CST (Common Spanning Tree)
d) STP Version 1 - What is the purpose of the root bridge in a Spanning Tree network?
a) It forwards the most traffic
b) It is the central point for path selection
c) It is used for routing traffic
d) It controls the VLAN configuration - Which of the following STP port roles is the port that forwards frames toward the root bridge?
a) Root port
b) Designated port
c) Blocked port
d) Alternate port - How does STP prevent network loops?
a) By blocking redundant links
b) By using VLAN tagging
c) By creating subnets
d) By enabling routing protocols - Which STP timer is used to define how long a switch should wait before confirming a topology change?
a) Hello time
b) Forward delay
c) Max age
d) Topology change time - What happens if the root bridge fails in an STP network?
a) The network will experience a broadcast storm
b) A new root bridge will be elected automatically
c) The network will be disconnected
d) The switch will drop all frames - Which STP state allows a port to forward frames?
a) Listening
b) Learning
c) Forwarding
d) Blocking - RSTP improves upon traditional STP by doing which of the following?
a) Reducing the number of port states
b) Allowing faster convergence
c) Using a single port for all VLANs
d) Both a and b - How can you manually configure a root bridge in an STP network?
a) By setting the bridge priority to a low value
b) By setting the bridge priority to a high value
c) By enabling RSTP
d) By assigning the IP address to the root bridge - What is the default spanning tree mode on Cisco switches?
a) RSTP
b) PVST+
c) CST
d) MSTP
Answers
| Qno | Answer (Option with the text) |
|---|---|
| 1 | b) 14 bytes |
| 2 | d) All of the above |
| 3 | b) To ensure the integrity of the frame |
| 4 | c) The type of protocol encapsulated in the frame |
| 5 | c) 64 bytes |
| 6 | b) Data Link Layer |
| 7 | b) Layer 2 (Data Link) |
| 8 | b) Based on the destination MAC address |
| 9 | a) Switches use flooding when they do not know the destination MAC address |
| 10 | d) All of the above |
| 11 | b) 00:1A:2B:3C:4D:5E |
| 12 | b) By listening to incoming frames and recording source MAC addresses |
| 13 | b) Broadcasts the frame to all ports |
| 14 | a) 01:00:5E:xx:xx:xx |
| 15 | b) The MAC addresses and associated ports |
| 16 | d) Both a and c |
| 17 | c) 1–4095 |
| 18 | b) It is the reserved VLAN for system use only |
| 19 | a) To carry traffic for multiple VLANs |
| 20 | c) IEEE 802.1Q |
| 21 | d) All of the above |
| 22 | c) Root bridge and port roles |
| 23 | b) Switches can be configured using a graphical user interface |
| 24 | d) vlan database |
| 25 | b) VLAN 1 |
| 26 | b) VLANs are manually configured on specific switch ports |
| 27 | b) It uses a VLAN management protocol to assign VLANs based on the MAC address |
| 28 | b) IEEE 802.1Q |
| 29 | b) 802.1Q |
| 30 | c) Trunk |
| 31 | a) RSTP |
| 32 | b) It is the central point for path selection |
| 33 | a) Root port |
| 34 | a) By blocking redundant links |
| 35 | b) Forward delay |
| 36 | b) A new root bridge will be elected automatically |
| 37 | c) Forwarding |
| 38 | d) Both a and b |
| 39 | a) By setting the bridge priority to a low value |
| 40 | b) PVST+ |