19 free Cisco 100-150 CCST Networking practice questions from the CertStash pack of 75, each with the correct answer and a full explanation. The rule is the same for every exam: ten free on the product page, 19 free here, all 75 in the pack, and each step includes the one before it.
Get all 75 questions (US$39) · Download the first 10 as a PDF · Read the study guide
Question 1
What is the most compressed valid format of the IPv6 address 2001:0db8:0000:0016:0000:001b:2000:0056?
Show answer and explanation
Correct answer: A. 2001:db8:0:16::1b:2000:56
IPv6 addresses are compressed by removing leading zeros in each hextet and replacing one contiguous sequence of all-zero hextets with a double colon (::). In 2001:0db8:0000:0000:0000:001b:2000:0056, the four consecutive zero hextets (positions 3-6) are replaced with ::, yielding 2001:db8::1b:2000:56. However, option A shows 2001:db8:0:16::1b:2000:56, which correctly compresses the address by removing leading zeros and applying the :: notation appropriately to the longest run of consecutive zeros.
Why the other options are wrong
- B. The double colon (::) can only be used once in an IPv6 address; using it twice is invalid.
- C. This incorrectly compresses 2000 to 2, which changes the actual hextet value.
- D. This uses the double colon twice and also incorrectly compresses 2000 to 2, both of which are invalid transformations.
Question 2
Which two statements are true about the IPv4 address of the default gateway configured on a host? (Choose two.) Note: You will receive partial credit for each correct selection.
Show answer and explanation
Correct answer: C, D. The default gateway is the IPv4 address of the router interface connected to the same local network as the host; The same default gateway IPv4 address is configured on each host on the local network.
The default gateway is the IPv4 address of the router interface on the same local network segment as the host, allowing the host to reach remote networks. All hosts on the same local network typically use the same default gateway address to route traffic outside their subnet. Option C is correct because the default gateway must be a router interface on the local network. Option D is correct because all hosts on the same subnet share the same default gateway to maintain consistent routing.
Why the other options are wrong
- A. The default gateway address does not need to be the first host address; it is simply a router interface address on the local network.
- B. The default gateway is not the Loopback0 interface; it must be a real interface connected to the same physical network as the host.
- E. Hosts typically learn the default gateway through DHCP or manual configuration, not through router advertisement messages (which are used for IPv6 prefix discovery).
Question 3
A local company requires two networks in two new buildings. The addresses used in these networks must be in the private network range. Which two address ranges should the company use? (Choose two.) Note: You will receive partial credit for each correct selection.
Show answer and explanation
Correct answer: B, C. 192.168.0.0 to 192.168.255.255; 172.16.0.0 to 172.31.255.255
RFC 1918 defines three ranges of private IPv4 addresses: 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255. Option B (192.168.0.0 to 192.168.255.255) and option C (172.16.0.0 to 172.31.255.255) are both valid private ranges that the company should use for their two networks.
Why the other options are wrong
- A. The 11.0.0.0 range is not part of the RFC 1918 private address space and is publicly routable.
- D. The 192.16.0.0 range is not a private address range; only 192.168.0.0 to 192.168.255.255 within the 192.x.x.x space is private.
Question 4
What is the CIDR prefix notation for a subnet mask of 255.255.0.0?
Show answer and explanation
Correct answer: B. /16
CIDR notation /n represents the number of consecutive 1 bits in the subnet mask. The mask 255.255.0.0 in binary is 11111111.11111111.00000000.00000000, which contains 16 consecutive 1 bits, making it /16.
Why the other options are wrong
- A. /8 corresponds to 255.0.0.0, which has only 8 bits set.
- C. /24 corresponds to 255.255.255.0, which has 24 bits set.
- D. /32 corresponds to 255.255.255.255, which has all 32 bits set.
Question 5
How is the following IP address written when using CIDR notation? Address: 192.168.0.16 Subnet Mask: 255.255.255.240
Show answer and explanation
Correct answer: D. 192.168.0.16 /28
The subnet mask 255.255.255.240 in binary is 11111111.11111111.11111111.11110000. Counting the 1 bits yields 28 consecutive ones, so the CIDR notation is /28. This can be verified by noting that 240 in decimal equals 11110000 in binary, contributing 4 ones to the final octet, giving 8+8+8+4=28 total.
Why the other options are wrong
- A. /30 corresponds to 255.255.255.252, not 255.255.255.240.
- B. /15 corresponds to 255.254.0.0, which is far too small a prefix.
- C. /24 corresponds to 255.255.255.0, not 255.255.255.240.
Question 6
Which address is a link-local IPv6 address?
Show answer and explanation
Correct answer: A. fe80::261:2eff:fe10:7561
Link-local IPv6 addresses always begin with the prefix fe80::/10, meaning they start with fe80 through febf. Option A (fe80::261:2eff:fe10:7561) begins with fe80, making it a valid link-local address used for communication on the local link only.
Why the other options are wrong
- B. ff01:0:0:0:0:0:0:2 starts with ff01, which indicates a multicast address, not a link-local address.
- C. 2001:db8:85a3:8d3:1319:8a2e:370:7348 starts with 2001, which is a global unicast address used on the internet.
- D. fdf8:f535:82e4::53 starts with fdf8, which is a unique local (private) address, not a link-local address.
Question 7
A support technician examines the front panel of a Cisco switch and sees 4 Ethernet cables connected in the first four ports. Ports 1, 2, and 3 have a green LED. Port 4 has a blinking green light. What is the state of the Port 4?
Show answer and explanation
Correct answer: B. Link is up and active.
On Cisco switches, a green LED on a port indicates the link is up. A steady green LED means the link is up with no activity, while a blinking (flickering) green LED indicates the link is up and actively transmitting or receiving data. Port 4's blinking green LED means data is actively flowing through that port.
Why the other options are wrong
- A. A steady green LED indicates no activity; a blinking green LED indicates activity.
- C. A blinking green LED does not indicate cable malfunction; cable issues typically result in an off or red LED.
- D. A blinking green LED does not indicate instability; it simply shows normal active data transmission on a healthy link.
Question 8
Which information is included in the header of a UDP segment?
Show answer and explanation
Correct answer: A. Port numbers
The UDP segment header contains source port, destination port, length, and checksum fields. Port numbers are essential components of the UDP header used to identify the sending and receiving applications. IP addresses are found in the IP header at Layer 3, MAC addresses are in the Data Link frame, and sequence numbers are a TCP feature, not UDP.
Why the other options are wrong
- B. Sequence numbers are a TCP feature used for ordered delivery, not present in UDP headers.
- C. IP addresses are contained in the IP packet header at Layer 3, not the UDP segment header.
- D. MAC addresses are found in the Data Link layer frame header, not in UDP segments.
Question 9
Which standard contains the specifications for Wi-Fi networks?
Show answer and explanation
Correct answer: A. IEEE 802.11
IEEE 802.11 is the international standard that specifies the technical standards for Wi-Fi wireless local area networks. GSM and LTE are cellular standards, IEEE 802.3 defines Ethernet wired networks, and EIA/TIA 568A is a standard for structured cabling and connector pinouts.
Why the other options are wrong
- B. GSM is a cellular mobile network standard, not a Wi-Fi standard.
- C. IEEE 802.3 defines Ethernet standards for wired networks, not wireless Wi-Fi.
- D. LTE is a cellular mobile network standard, not a Wi-Fi standard.
- E. EIA/TIA 568A is a wiring standard for network cables and connectors, not Wi-Fi specifications.
Question 10
During the data encapsulation process, which OSI layer adds a header that contains MAC addressing information and a trailer used for error checking?
Show answer and explanation
Correct answer: D. Data Link
The Data Link layer (Layer 2) adds a header containing MAC addressing information and a trailer containing error-checking information, typically a frame check sequence (FCS). This layer is responsible for framing data and ensuring reliable transmission between devices on the same network segment. The Network layer adds IP addresses, the Transport layer adds port information, and the Session layer manages session control.
Why the other options are wrong
- A. The Network layer adds IP address information in its header but does not add MAC addresses or error-checking trailers.
- B. The Transport layer adds port numbers and handles segmentation but does not add MAC addresses or frame trailers.
- C. The Session layer manages session control and does not deal with MAC addresses or frame-level error checking.
What people say about the full 100-150 pack 5.0 from 2
Question 11
Which command will display the following output?
Show answer and explanation
Correct answer: B. show cdp neighbor
The output displays information about neighboring devices discovered through CDP (Cisco Discovery Protocol), including Device ID, Local Interface, Holdtime, Capability codes, Platform, and Port ID. This is the exact format and content produced by the 'show cdp neighbor' command, which discovers and displays information about directly connected Cisco devices and other network equipment.
Why the other options are wrong
- A. The 'show inventory' command displays hardware inventory information such as chassis, modules, and power supplies, not neighbor discovery data.
- C. The 'show mac-address-table' command displays MAC address table entries with learned MAC addresses and their associated ports and VLANs, not device neighbor information.
- D. The 'show ip interface' command displays IP configuration details for interfaces including IP addresses, status, and IP statistics, not CDP neighbor discovery information.
Question 12
Which command will display all the current operational settings configured on a Cisco router?
Show answer and explanation
Correct answer: B. show running-config
The 'show running-config' command displays the currently active configuration that the router is using. This includes all operational settings that are presently in effect, as opposed to the startup configuration which is saved to memory.
Why the other options are wrong
- A. show startup-config displays the saved configuration, not the current operational settings.
- C. show protocols displays information about configured protocols, not the full configuration.
- D. show version displays router hardware and software version information, not configuration settings.
Question 13
A host is given the IP address 172.16.100.25 and the subnet mask 255.255.252.0. What is the CIDR notation for this address?
Show answer and explanation
Correct answer: B. 172.16.100.25 /22
The mask 255.255.252.0 has 8 + 8 + 6 + 0 network bits, because 252 is 11111100 in binary. That totals 22 bits, so the address in CIDR notation is 172.16.100.25/22.
Why the other options are wrong
- A. /21 corresponds to 255.255.248.0, not 255.255.252.0.
- C. /23 corresponds to 255.255.254.0, not 255.255.252.0.
- D. /20 corresponds to 255.255.240.0, not 255.255.252.0.
Question 14
Which address is included in the 192.168.200.0/24 network?
Show answer and explanation
Correct answer: B. 192.168.200.13
The network 192.168.200.0/24 encompasses all addresses from 192.168.200.0 through 192.168.200.255. Option B (192.168.200.13) falls within this range, as it has the same network portion (192.168.200) and a valid host portion (13). Options A, C, and D have different third octets and therefore belong to different networks.
Why the other options are wrong
- A. 192.168.1.13 has a different network address (192.168.1.0/24) and is not in the 192.168.200.0/24 network.
- C. 192.168.199.13 has a different network address (192.168.199.0/24) and is not in the 192.168.200.0/24 network.
- D. 192.168.201.13 has a different network address (192.168.201.0/24) and is not in the 192.168.200.0/24 network.
Question 15
At which OSI layer is the data stream broken up into segments that include source and destination port numbers?
Show answer and explanation
Correct answer: A. Transport
The Transport layer (Layer 4) breaks the data stream into segments and adds source and destination port numbers to identify the sending and receiving applications. This is a core function of Transport layer protocols like TCP and UDP. The Data Link layer works with frames, the Network layer with packets, and the Session layer manages application sessions rather than data segmentation.
Why the other options are wrong
- B. The Data Link layer creates frames, not segments, and does not add port numbers.
- C. The Session layer manages dialog control and sessions, not data segmentation.
- D. The Network layer creates packets and adds IP addresses, not port numbers or segments.
Question 16
You want to store files that will be accessible by every user on your network. Which endpoint device do you need?
Show answer and explanation
Correct answer: D. Server
A server is the endpoint device designed to store files and make them accessible to multiple users across a network. Servers provide centralized file storage, access control, and sharing capabilities that are essential for network-wide file accessibility.
Why the other options are wrong
- A. A switch is a networking device that forwards data frames, not a storage device.
- B. An access point provides wireless connectivity, not file storage.
- C. A hub is a basic networking device for connecting computers, not for centralized file storage.
Question 17
You need to connect a computer's network adapter to a switch using a 1000BASE-T cable. Which connector should you use?
Show answer and explanation
Correct answer: A. RJ-45
1000BASE-T is a Gigabit Ethernet standard that uses unshielded twisted pair (UTP) cable terminated with RJ-45 connectors. The RJ-45 is the standard connector for all modern Ethernet connections including 1000BASE-T.
Why the other options are wrong
- B. OS2 LC is a fiber optic connector, not used for copper-based 1000BASE-T.
- C. Coax connectors are used for older cable types like 10BASE2, not modern Ethernet.
- D. RJ-11 is a telephone connector with fewer pins, not suitable for Ethernet.
Question 18
Which type of connector should you use to terminate unshielded twisted pair cable?
Show answer and explanation
Correct answer: A. RJ-45
Unshielded twisted pair (UTP) cable is terminated using RJ-45 connectors. This is the standard for Ethernet cabling in networking, used for all modern twisted pair installations.
Why the other options are wrong
- B. ST is a fiber optic connector, not used for twisted pair cable.
- C. SC is a fiber optic connector, not used for twisted pair cable.
- D. BNC is a coaxial connector used for older cable types, not twisted pair.
Question 19
Which network technology is not impacted by electromagnetic and radio wave interference?
Show answer and explanation
Correct answer: B. Fiber
Fiber optic cable is immune to electromagnetic and radio wave interference because it transmits data using light pulses through glass or plastic fibers rather than electrical signals. This makes it ideal for environments with high interference.
Why the other options are wrong
- A. Copper cables are susceptible to electromagnetic interference.
- C. Wireless networks are inherently affected by radio wave interference.
- D. Twisted pair cable, while partially mitigated by its design, is still vulnerable to electromagnetic interference.
That was 19 of 75.
The full Cisco 100-150 CCST Networking pack has all 75 questions, each with the answer, the explanation and why the other options are wrong, plus a questions-only copy for timed runs. US$39, paid once, with free monthly updates and a pass-or-your-money-back guarantee.
Not ready yet? Get the first 26 free as one PDF by email. Get the Half Pack →