Networking Intermediate

What is ICMP (Internet Control Message Protocol)?

A network protocol used for diagnostic and error reporting, including ping and traceroute functionality.

ICMP sends error messages and operational information between network devices. Ping uses ICMP Echo Request/Reply to test reachability and measure round-trip time. Traceroute uses ICMP Time Exceeded messages to discover the network path.

Common ICMP messages include Destination Unreachable, Time Exceeded, Redirect, and Source Quench. While essential for network diagnostics, ICMP is often restricted by firewalls to prevent information disclosure and DDoS amplification attacks.

Related Terms

An intermediary server that forwards requests between clients and destination servers, providing caching, filtering, or anonymity.

A protocol that automatically assigns IP addresses and network configuration to devices on a network.

DNS over HTTPS (DoH)

A protocol that encrypts DNS queries by sending them over HTTPS, preventing eavesdropping and manipulation of DNS traffic.

A compact method for specifying IP addresses and their associated routing prefix using a slash followed by the prefix length.

SNMP (Simple Network Management Protocol)

A protocol for monitoring and managing network devices like routers, switches, servers, and printers remotely.

Network Segmentation

The practice of dividing a network into isolated segments to improve security, performance, and management.

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