Sample Questions and answers
What is the purpose of a default gateway?
To route traffic destined for outside the local subnet
B. To assign IP addresses to hosts
C. To act as a DNS server
D. To connect wireless clients
Answer: A. To route traffic destined for outside the local subnet
Explanation: Default gateway forwards packets to remote networks.
What is the function of the Cisco IOS command enable secret?
Sets an encrypted password for privileged EXEC mode
B. Enables secret debugging mode
C. Shows secret passwords
D. Enables console access
Answer: A. Sets an encrypted password for privileged EXEC mode
Explanation: Provides secure encrypted password protection.
What is the port number used by HTTPS?
443
B. 80
C. 23
D. 21
Answer: A. 443
Explanation: HTTPS uses TCP port 443 for secure web traffic.
What type of routing protocol is RIP?
Distance-vector
B. Link-state
C. Hybrid
D. Path-vector
Answer: A. Distance-vector
Explanation: RIP shares routing tables periodically and uses hop count as metric.
Which protocol does a Cisco switch use to learn the VLANs allowed on a trunk port?
VTP
B. STP
C. CDP
D. LLDP
Answer: A. VTP
Explanation: VLAN Trunking Protocol manages VLAN info between switches.
What is the purpose of NAT?
To translate private IP addresses to public IP addresses
B. To encrypt data
C. To assign IP addresses
D. To increase bandwidth
Answer: A. To translate private IP addresses to public IP addresses
Explanation: Allows multiple devices to share a public IP for internet access.
Which command disables domain lookup on a Cisco router?
no ip domain-lookup
B. no domain lookup
C. disable dns
D. no dns
Answer: A. no ip domain-lookup
Explanation: Prevents the router from trying to translate mistyped commands as domain names.
What is the default port for Telnet?
23
B. 22
C. 21
D. 80
Answer: A. 23
Explanation: Telnet uses TCP port 23 but is unencrypted.
Which routing protocol is classless?
OSPF
B. RIP version 1
C. IGRP
D. None
Answer: A. OSPF
Explanation: OSPF supports VLSM and CIDR, making it classless.
What is the purpose of the command show ip route?
Displays the router’s routing table
B. Shows interface IP addresses
C. Displays running configuration
D. Shows ARP table
Answer: A. Displays the router’s routing table
Explanation: Useful to check routes learned and installed.
What is the function of the traceroute command?
Shows the path packets take to a destination
B. Tests if a host is reachable
C. Displays the routing table
D. Displays DNS records
Answer: A. Shows the path packets take to a destination
Explanation: Helps identify routing problems or delays.
Which wireless standard operates at 5 GHz and supports up to 1.3 Gbps?
802.11ac
B. 802.11b
C. 802.11g
D. 802.11n
Answer: A. 802.11ac
Explanation: 802.11ac is a fast 5 GHz Wi-Fi standard.
What does the acronym SSH stand for?
Secure Shell
B. Secure Socket Hypertext
C. Simple Shell Handler
D. Secure Session Host
Answer: A. Secure Shell
Explanation: Provides encrypted command line access.
Which command will display a switch’s MAC address table?
show mac address-table
B. show arp
C. show interface
D. show vlan
Answer: A. show mac address-table
Explanation: Lists MAC addresses and their associated ports.
Which Cisco IOS command configures an interface description?
description [text]
B. set description [text]
C. interface description [text]
D. config description [text]
Answer: A. description [text]
Explanation: Helps identify interface purpose or connection.
Which layer of the OSI model manages data flow control?
Transport
B. Network
C. Session
D. Data Link
Answer: A. Transport
Explanation: Transport layer protocols like TCP handle flow control.
What is a characteristic of UDP?
Connectionless and unreliable
B. Connection-oriented and reliable
C. Encrypts data
D. Requires handshake before transmission
Answer: A. Connectionless and unreliable
Explanation: UDP sends packets without acknowledgment.
What is the purpose of the Cisco command enable?
Enters privileged EXEC mode
B. Enables an interface
C. Starts the router
D. Saves configuration
Answer: A. Enters privileged EXEC mode
Explanation: Needed to access advanced commands.
What is the subnet mask for a /30 network?
255.255.255.252
B. 255.255.255.248
C. 255.255.255.0
D. 255.255.255.224
Answer: A. 255.255.255.252
Explanation: Provides 4 IP addresses (2 usable hosts).
Which command enables interface GigabitEthernet0/1?
interface GigabitEthernet0/1 followed by no shutdown
B. enable interface GigabitEthernet0/1
C. ip enable GigabitEthernet0/1
D. turn on GigabitEthernet0/1
Answer: A. interface GigabitEthernet0/1 followed by no shutdown
Explanation: The interface must be enabled explicitly.
Which protocol is used to obtain IP addresses dynamically?
DHCP
B. DNS
C. SMTP
D. FTP
Answer: A. DHCP
Explanation: DHCP servers lease IPs to clients dynamically.
What is the default subnet mask for a Class B IP address?
255.255.0.0
B. 255.0.0.0
C. 255.255.255.0
D. 255.255.255.255
Answer: A. 255.255.0.0
Explanation: Class B addresses have a default subnet mask of 255.255.0.0.
Which Cisco IOS command is used to configure an IP address on an interface?
ip address [IP] [Subnet Mask]
B. set ip [IP] [Subnet Mask]
C. interface ip [IP] [Subnet Mask]
D. config ip [IP] [Subnet Mask]
Answer: A. ip address [IP] [Subnet Mask]
Explanation: This command assigns an IP and subnet mask to an interface in interface configuration mode.
What does the show interfaces command display?
Status and statistics for all interfaces
B. IP routing table
C. MAC address table
D. DHCP leases
Answer: A. Status and statistics for all interfaces
Explanation: Useful for troubleshooting physical and data link layer issues.
What is the primary benefit of using OSPF over RIP?
Faster convergence and support for VLSM
B. Simplicity and easier setup
C. Uses hop count only
D. Uses UDP as transport protocol
Answer: A. Faster convergence and support for VLSM
Explanation: OSPF is a link-state protocol that converges faster and supports variable length subnet masks.
Which protocol provides automatic IP address assignment?
DHCP
B. FTP
C. SNMP
D. DNS
Answer: A. DHCP
Explanation: DHCP dynamically assigns IP addresses to hosts on a network.
What type of device filters traffic based on MAC addresses?
Switch
B. Router
C. Hub
D. Firewall
Answer: A. Switch
Explanation: Switches use MAC addresses to forward traffic within a LAN.
Which layer of the OSI model is responsible for establishing, managing, and terminating sessions?
Session
B. Transport
C. Network
D. Data Link
Answer: A. Session
Explanation: The Session layer manages sessions between applications.
What is the default VLAN on Cisco switches?
VLAN 1
B. VLAN 10
C. VLAN 100
D. VLAN 0
Answer: A. VLAN 1
Explanation: VLAN 1 is the default management VLAN on Cisco switches.
What command on a Cisco router displays current TCP connections?
show tcp brief
B. show ip tcp
C. show connections
D. show sessions
Answer: A. show tcp brief
Explanation: Displays TCP connection status and ports.
Which protocol encrypts traffic for secure communication over unsecured networks?
IPsec
B. FTP
C. SMTP
D. Telnet
Answer: A. IPsec
Explanation: IPsec encrypts IP packets for secure VPN tunnels.
What is the function of STP (Spanning Tree Protocol)?
Prevents loops in a Layer 2 network
B. Assigns IP addresses
C. Routes IP packets
D. Provides wireless security
Answer: A. Prevents loops in a Layer 2 network
Explanation: STP blocks redundant paths to prevent broadcast storms.
Which address type is FF-FF-FF-FF-FF-FF?
Broadcast MAC address
B. Multicast MAC address
C. Unicast MAC address
D. Anycast MAC address
Answer: A. Broadcast MAC address
Explanation: Used to send frames to all devices on a LAN.
What is the maximum number of hosts on a subnet with a /28 mask?
14
B. 16
C. 30
D. 62
Answer: A. 14
Explanation: /28 equals 255.255.255.240, which provides 16 IPs, 14 usable hosts.
What protocol is used to securely manage network devices?
SSH
B. Telnet
C. FTP
D. HTTP
Answer: A. SSH
Explanation: SSH encrypts management traffic, providing secure remote access.
Which command enables port security on a switch interface?
switchport port-security
B. port-security enable
C. enable port-security
D. security port-enable
Answer: A. switchport port-security
Explanation: Activates port security features on the interface.
Which OSI layer is responsible for data encryption and decryption?
Presentation
B. Application
C. Network
D. Transport
Answer: A. Presentation
Explanation: Presentation layer formats data and manages encryption.
What is the default administrative distance of OSPF?
110
B. 90
C. 120
D. 100
Answer: A. 110
Explanation: OSPF has an administrative distance of 110.
Which Cisco IOS command is used to enter global configuration mode?
configure terminal
B. config global
C. global-config
D. config mode
Answer: A. configure terminal
Explanation: Allows access to device configuration commands.
Which protocol uses port 69 for data transfer?
TFTP
B. FTP
C. SMTP
D. HTTP
Answer: A. TFTP
Explanation: TFTP is a simple, UDP-based file transfer protocol on port 69.
What is the result of the command no shutdown on an interface?
Enables the interface
B. Disables the interface
C. Resets the interface
D. Configures the interface
Answer: A. Enables the interface
Explanation: By default, interfaces may be shut down; this command activates them.
What command displays the current ARP cache?
show arp
B. show ip arp
C. show mac-address-table
D. show ip interface
Answer: A. show arp
Explanation: Lists IP to MAC address mappings cached on the device.
Which layer of the OSI model is responsible for error detection at the frame level?
Data Link
B. Network
C. Transport
D. Physical
Answer: A. Data Link
Explanation: The Data Link layer detects errors using CRC checks.
What is the purpose of the Cisco command reload?
Reboots the device
B. Saves the configuration
C. Displays current config
D. Clears the interface
Answer: A. Reboots the device
Explanation: Restarts the router or switch.
What protocol is used to send email?
SMTP
B. FTP
C. HTTP
D. SNMP
Answer: A. SMTP
Explanation: Simple Mail Transfer Protocol is used for sending emails.
Which port does SNMP use by default?
161
B. 162
C. 80
D. 23
Answer: A. 161
Explanation: SNMP agents listen on UDP port 161.
What is the default priority value in STP?
32768
B. 4096
C. 0
D. 1
Answer: A. 32768
Explanation: The default bridge priority for STP is 32768.
Which of the following is NOT a private IP address range?
192.168.128.0
B. 172.32.0.0
C. 10.0.0.0
D. 192.168.0.0
Answer: B. 172.32.0.0
Explanation: 172.16.0.0 to 172.31.255.255 is private; 172.32.0.0 is public.
What is the purpose of a collision domain?
The network area where packets may collide
B. An IP subnet
C. A broadcast domain
D. A VLAN
Answer: A. The network area where packets may collide
Explanation: Collisions occur on half-duplex Ethernet segments.
Which command shows the running configuration?
show running-config
B. show config
C. show startup-config
D. show run
Answer: A. show running-config
Explanation: Displays the current active configuration in RAM.
Which wireless standard supports speeds up to 54 Mbps?
802.11g
B. 802.11b
C. 802.11n
D. 802.11ac
Answer: A. 802.11g
Explanation: 802.11g supports up to 54 Mbps in the 2.4 GHz band.
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