ping

ping is a network diagnostic command that tests host reachability, measures round-trip latency, and detects packet loss by sending ICMP echo request packets on Linux, macOS, and Windows.

What ping Does and When to Use It

The ping command sends Internet Control Message Protocol (ICMP) echo request packets to a target host and waits for ICMP echo reply packets. Each reply includes the round-trip time (RTT) in milliseconds, the Time to Live (TTL) value, and the ICMP sequence number. After completing, ping prints a summary with minimum, average, and maximum RTT along with the packet loss percentage.

The ping command is the first tool to reach for when diagnosing network connectivity issues. It answers the fundamental question: "Can my machine reach this host?" Use ping to confirm whether a server is online, measure baseline latency to a remote host, and detect intermittent packet loss on a network path.

The ping command cannot determine wherea connectivity failure occurs along the network path. If ping fails, the problem could be at the destination host, at a router in the middle, at the local gateway, or at the local firewall. Use the traceroute commandto identify the specific hop where packets fail. For a detailed comparison, see ping vs traceroute: when to use which.

Core Concepts of ping

ICMP Protocol and ping

The ping command uses ICMP (Internet Control Message Protocol), a network-layer protocol separate from TCP and UDP. ICMP echo requests and replies do not use port numbers — they operate at the IP layer. Many firewalls and cloud security groups block ICMP traffic by default, which means a host can be fully operational and reachable on TCP ports (HTTP, SSH) while appearing unreachable to ping.

Ping Packet Loss and Network Quality

The ping command reports packet loss as a percentage of sent packets that received no reply. A result of 0% packet loss indicates a stable connection. Packet loss between 1% and 5% suggests network congestion or an unreliable link. Packet loss above 10% indicates a significant network problem that affects application performance. A result of 100% packet loss means either the host is down, ICMP is blocked, or a routing failure prevents packets from reaching the destination.

Ping Round-Trip Time (RTT) and Latency

The ping command measures round-trip time in milliseconds — the total time for a packet to travel from the source to the destination and back. RTT below 50 ms is typical for hosts on the same continent. RTT between 100–200 ms is expected for intercontinental connections. RTT above 300 ms degrades real-time applications like VoIP and video conferencing.

Common Tasks with ping

How to Ping a Host with a Limited Packet Count

Send exactly 5 ICMP echo requests and stop:

ping -c 5 example.com

On Windows, the equivalent flag is -n: ping -n 5 example.com.

How to Ping an IP Address to Bypass DNS

Test raw network connectivity without DNS resolution:

ping -c 3 8.8.8.8

If this succeeds but ping example.com fails, the issue is DNS resolution, not network connectivity. Use the host commandor the dig commandto diagnose DNS.

For detailed usage, see How to test network connectivity with ping.

ping Troubleshooting

Related Tools and Guides

The traceroute commandreveals the full network path to a host, identifying each router hop and its latency — use traceroute when ping fails and you need to find wherethe failure occurs. The host commandand the dig commanddiagnose DNS resolution issues that ping alone cannot distinguish from network failures.