In traceroute, the three numbers typically refer to the TTL (Time-to-Live) values used in successive ICMP (Internet Control Message Protocol) Echo Request packets sent to trace the route to a destination. TTL is a field in the IP header that specifies the maximum number of router hops (or network segments) that a packet can traverse before being discarded. Traceroute starts by sending packets with a TTL of 1, then 2, and incrementally increases the TTL until reaching the destination. Each TTL value corresponds to a different set of routers along the path to the destination, allowing traceroute to map the network path taken by packets from the source to the destination.
In traceroute, the three values often represent the IP addresses or hostnames of the routers or devices encountered along the network path to the destination. As traceroute sends ICMP Echo Request packets with increasing TTL values, it records the IP addresses of the routers that forward the packets towards the destination. These values show the specific routers or network devices that handle the packet as it progresses towards the final destination, providing insight into the network topology and routing path taken by packets.
The three times in traceroute typically refer to the round-trip time (RTT) measurements recorded for each TTL value sent during the traceroute process. Traceroute measures the time it takes for each ICMP Echo Request packet to travel from the source to an intermediate router and then back from the router to the source. By sending multiple packets (often three) per TTL value and recording the RTT for each, traceroute provides a picture of the latency experienced at each hop along the network path. These RTT values help diagnose network performance issues, identify delays, and assess the efficiency of data transmission between network segments.
Traceroute sends three packets per TTL value primarily for reliability and statistical accuracy. By sending multiple packets, traceroute can obtain a more consistent measurement of round-trip times and network path characteristics. If one ICMP Echo Request packet is lost or delayed due to network congestion or other factors, traceroute can still gather data from the remaining packets to construct a comprehensive view of the network path. This redundancy improves the reliability of traceroute results and ensures that administrators obtain accurate information about network routing and performance.
tracert (traceroute in Windows), the numbers displayed typically represent the TTL values used for each ICMP Echo Request packet sent during the tracing process. These numbers indicate the maximum number of router hops or network segments that each packet can traverse before being discarded. As tracert progresses through each TTL value, it records the IP addresses or hostnames of the routers encountered along the path to the destination, providing a sequential view of the network route taken by packets. This numeric sequence helps administrators visualize the number of hops and the specific network devices involved in transmitting packets from the source to the destination.