This 200-901 practice question tests your understanding of network fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
C:\> ping 192.168.1.1
Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
What does a TTL of 128 indicate about the destination host?
C:\> ping 192.168.1.1
Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Reply from 192.168.1.1: bytes=32 time<1ms TTL=128
Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
A
It is a network switch
Why wrong: Switches operate at Layer 2 and do not typically originate pings; if they do, they often use TTL 255.
B
It is a Cisco router
Why wrong: Cisco devices typically send packets with TTL 255, not 128.
C
It is a Windows host
Windows uses a default TTL of 128.
D
It is a Linux host
Why wrong: Linux and macOS typically use a default TTL of 64.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It is a Windows host
The Time-to-Live (TTL) value in an IP packet is decremented by each router that forwards the packet. When a host receives a packet, the remaining TTL value can indicate the operating system of the source that sent it. Windows operating systems typically set the initial TTL to 128, so a TTL of 128 in a received packet strongly suggests the destination host (the sender of that packet) is a Windows host.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
It is a network switch
Why it's wrong here
Switches operate at Layer 2 and do not typically originate pings; if they do, they often use TTL 255.
✗
It is a Cisco router
Why it's wrong here
Cisco devices typically send packets with TTL 255, not 128.
✓
It is a Windows host
Why this is correct
Windows uses a default TTL of 128.
Related concept
Read the scenario before looking for a memorised answer.
✗
It is a Linux host
Why it's wrong here
Linux and macOS typically use a default TTL of 64.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the common misconception that TTL values are set by routers or switches, rather than by the originating host's operating system, leading candidates to incorrectly associate a TTL of 128 with a specific network device instead of a Windows host.
Detailed technical explanation
How to think about this question
The initial TTL value is set by the operating system's IP stack according to its default configuration, as defined in RFC 791. While 128 is the default for Windows (e.g., Windows 10, Server 2019), some older Windows versions or custom configurations may use 128 or 64. In real-world network troubleshooting, a TTL of 128 in a ping reply can quickly identify a Windows machine without needing to query its hostname or perform a port scan.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It is a Windows host — The Time-to-Live (TTL) value in an IP packet is decremented by each router that forwards the packet. When a host receives a packet, the remaining TTL value can indicate the operating system of the source that sent it. Windows operating systems typically set the initial TTL to 128, so a TTL of 128 in a received packet strongly suggests the destination host (the sender of that packet) is a Windows host.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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