How to troubleshoot network connectivity with ping, traceroute, and mtr

    Introduction

    When a server or website is unreachable, the first step is to determine where the connection fails. Three essential command-line tools help you diagnose network issues: ping, traceroute, and mtr.

    ping — Test basic connectivity

    ping sends ICMP echo requests to a host and measures the round-trip time. It answers the most basic question: "Can I reach this host?"

    Basic usage

    ping example.com

    On Linux, ping runs continuously until you press Ctrl+C. To send a specific number of packets:

    ping -c 5 example.com

    Reading the output

    PING example.com (93.184.216.34): 56 data bytes
64 bytes from 93.184.216.34: icmp_seq=0 ttl=56 time=11.6 ms
64 bytes from 93.184.216.34: icmp_seq=1 ttl=56 time=11.4 ms
64 bytes from 93.184.216.34: icmp_seq=2 ttl=56 time=11.5 ms

--- example.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss
round-trip min/avg/max = 11.4/11.5/11.6 ms

    What to look for

    Symptom Possible cause
    100% packet loss Host is down, firewall blocking ICMP, or routing issue
    High latency (>200 ms) Network congestion, geographic distance, or routing inefficiency
    Intermittent packet loss (1–20%) Network congestion, faulty hardware, or ISP issue
    Destination Host Unreachable No route to the host; check routing tables and gateway
    Name or service not known DNS resolution failure; check DNS settings

    Useful options

    Option Description
    ping -c 10 host Send exactly 10 packets
    ping -i 0.2 host Send packets every 0.2 seconds (faster)
    ping -s 1400 host Use a larger packet size (test MTU issues)
    ping -4 host Force IPv4
    ping -6 host Force IPv6

    traceroute — Trace the path to a host

    traceroute shows every router (hop) between your machine and the destination. It helps identify where a connection fails or slows down.

    Basic usage

    traceroute example.com

    On some systems, you may need to install it:

    sudo apt install traceroute    # Debian/Ubuntu
sudo yum install traceroute    # AlmaLinux/RHEL

    Reading the output

    traceroute to example.com (93.184.216.34), 30 hops max, 60 byte packets
 1  gateway (192.168.1.1)  0.5 ms  0.4 ms  0.3 ms
 2  isp-router (10.0.0.1)  3.2 ms  3.1 ms  3.0 ms
 3  core-router (172.16.0.1)  8.5 ms  8.4 ms  8.3 ms
 4  * * *
 5  target (93.184.216.34)  11.5 ms  11.4 ms  11.3 ms

    Each line is a hop. The three time values are round-trip times for three probe packets. Asterisks (* * *) mean the hop did not respond (it may be blocking ICMP, not necessarily a failure).

    What to look for

    Symptom Possible cause
    Sudden jump in latency at a specific hop Congestion or issue at that router/network
    All hops after a certain point show * * * Firewall blocking or host down beyond that point
    Trace ends before reaching the target Routing problem or firewall dropping packets

    TCP traceroute (bypass ICMP blocks)

    Some firewalls block ICMP but allow TCP. Use tcptraceroute or:

    traceroute -T -p 443 example.com

    mtr — Combined ping + traceroute

    mtr (My Traceroute) combines ping and traceroute into a single real-time diagnostic tool. It continuously sends packets and shows per-hop packet loss and latency statistics.

    Installation

    sudo apt install mtr    # Debian/Ubuntu
sudo yum install mtr    # AlmaLinux/RHEL

    Basic usage

    mtr example.com

    This opens an interactive, real-time display. Press q to quit.

    Generate a report

    For sharing with support teams, use report mode:

    mtr -r -c 100 example.com

    This sends 100 packets and prints a summary:

    HOST: myserver              Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. gateway                 0.0%   100    0.3   0.4   0.2   1.1   0.1
  2. isp-router              0.0%   100    3.1   3.2   2.8   5.4   0.3
  3. core-router             2.0%   100    8.5   8.7   8.1  12.3   0.5
  4. target                  0.0%   100   11.4  11.6  11.2  14.1   0.4

    Key columns

    Column Description
    Loss% Percentage of packets lost at this hop
    Snt Number of packets sent
    Last Latency of the last packet (ms)
    Avg Average latency (ms)
    Best Lowest latency observed (ms)
    Wrst Highest latency observed (ms)
    StDev Standard deviation (higher = more jitter)

    When to use each tool

    Scenario Tool
    Quick check if a host is reachable ping
    Find where a connection fails traceroute
    Ongoing network quality analysis mtr
    Generate a report for support mtr -r -c 100

    Tips for reporting network issues

    When contacting support about a network problem, include:

    1. An mtr report from your machine to the target: mtr -r -c 100 target-ip
    2. A reverse mtr report from the server back to you (if you have SSH access)
    3. The time and timezone when the issue occurred
    4. Whether the issue is constant or intermittent
    Published