A traceroute works by sending Internet Control Message Protocol (ICMP) packets, and every router involved in transferring the data gets these packets. The ICMP packets provide information about whether the routers used in the transmission are able to effectively transfer the data.

Does traceroute use ICMP or UDP?

On Windows, tracert sends ICMP Echo Request packets, rather than the UDP packets traceroute sends by default. The time-to-live (TTL) value, also known as hop limit, is used in determining the intermediate routers being traversed towards the destination.

Does traceroute require ICMP?

Traceroute uses ICMP messages and TTL fields in the IP address header to function. Traceroute tools are typically included as a utility by operating systems such as Windows and Unix. Traceroute utilities based on TCP are also available.