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Network+

Understanding Network Latency and How to Reduce It

This post explains what network latency is, what causes it, and how to measure and reduce it using tools like ping and traceroute. Written for Network+ learners, it covers exam objective 5.4 with practical examples and actionable troubleshooting steps.

Jay Whale

• 3 min read
Understanding Network Latency and How to Reduce It

If you have ever noticed a video call freezing at the worst possible moment, or a game lagging right when it matters most, you have experienced the effects of network latency. It is one of the most common performance complaints in networking, and understanding it is a core skill for anyone working toward their Network+ certification or troubleshooting real-world issues.

What Is Network Latency?

Network latency is the time it takes for data to travel from one point to another across a network. It is measured in milliseconds (ms), and lower is always better. You will often hear it referred to as network delay, and the two terms are essentially interchangeable in most conversations.

Think of it like mailing a letter. The time between dropping it in the mailbox and the recipient opening it is the latency. The actual speed of the postal truck is your bandwidth. You can have a very fast truck (high bandwidth) but still have slow delivery if the truck has to make twenty stops along the way (high latency).

What Causes Latency?

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Several factors contribute to network delay, and being able to identify them is critical for troubleshooting:

  • Propagation delay: the time it physically takes a signal to travel through a medium like fiber or copper. The longer the physical distance, the higher this delay.
  • Processing delay: the time a device like a router or switch takes to examine a packet and decide where to forward it.
  • Queuing delay: the time a packet spends waiting in line inside a router or switch when traffic is congested.
  • Transmission delay: the time it takes to push all of a packet's bits onto the wire, which is influenced by link speed and packet size.

How to Measure Latency

The simplest tool for measuring latency is ping. It sends ICMP echo request packets to a target and measures how long it takes to get a reply. Here is an example of what that looks like from a Windows or Linux terminal:

ping google.com

PING google.com (142.250.80.46): 56 data bytes
64 bytes from 142.250.80.46: icmp_seq=0 ttl=118 time=12.4 ms
64 bytes from 142.250.80.46: icmp_seq=1 ttl=118 time=11.9 ms
64 bytes from 142.250.80.46: icmp_seq=2 ttl=118 time=12.1 ms

--- google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss
round-trip min/avg/max = 11.9/12.1/12.4 ms

The time value in each line is your round-trip latency in milliseconds. A result under 50 ms is generally excellent for most applications. Values above 150 ms will often cause noticeable issues in voice and video calls.

For a hop-by-hop view of where delay is being introduced, use traceroute on Linux or Mac, or tracert on Windows. This shows you the latency at each router along the path to your destination.

How to Reduce Latency

Once you understand what is causing the delay, you can take steps to improve performance. Here are practical approaches:

  • Reduce physical distance: choose servers or cloud regions geographically closer to your users. Content Delivery Networks (CDNs) exist specifically to solve this problem.
  • Upgrade your connection: older technologies like DSL or cable can introduce higher latency compared to fiber optic connections.
  • Address congestion: implement Quality of Service (QoS) policies to prioritize latency-sensitive traffic like voice and video over bulk transfers like backups.
  • Check your equipment: old routers and switches with slow CPUs can introduce significant processing delay. Replacing aging hardware often yields immediate improvements.
  • Use wired connections: Wi-Fi adds variable latency due to wireless interference and retransmissions. A wired Ethernet connection is almost always more consistent.
  • Minimize hops: every router a packet passes through adds a small amount of delay. Simplifying your network topology where possible reduces overall latency.

Why It Matters for Network+

Understanding network latency is directly tied to CompTIA Network+ exam objective 5.4, which covers network troubleshooting methodologies and tools. The exam expects you to recognize latency as a performance symptom, understand its causes, and know which tools (ping, traceroute) are used to measure and isolate it. These skills translate directly into real troubleshooting scenarios.

What's Next

Now that you understand latency and how to measure it, the next step is exploring packet loss: what causes it, how it interacts with latency, and how it can make even a low-latency connection feel unusable. We will also dig deeper into traceroute output and how to read it like a pro. Stay tuned for that post coming up next in this series.

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If you want to go beyond manual ping tests and get continuous visibility into latency across your network, PRTG Network Monitor is a solid choice — it tracks round-trip times, alerts you when thresholds are breached, and gives you historical data to spot patterns over time. PRTG Network Monitor, SolarWinds Network Performance Monitor and ThousandEyes.

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