# Field documentation for ICMP, TCP and HTTP synthetic monitor
**URL:** https://discuss.elastic.co/t/field-documentation-for-icmp-tcp-and-http-synthetic-monitor/372674
**Category:** Elastic Observability
**Tags:** elastic-stack-monitoring
**Created:** [December 31, 2024, 11:22pm UTC](https://discuss.elastic.co/t/field-documentation-for-icmp-tcp-and-http-synthetic-monitor/372674 "2024-12-31T23:22:23Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Yechezkal\_Gutfreund](https://discuss.elastic.co/u/Yechezkal_Gutfreund)
#### Post date: [December 31, 2024, 11:22pm UTC](https://discuss.elastic.co/t/field-documentation-for-icmp-tcp-and-http-synthetic-monitor/372674/1 "2024-12-31T23:22:23Z")
I have been unsuccessful in hunting down some documentation on the fields returned by the synthetic monitors (specifically, I want to understand the differences between
`icmp.rtt.us`
` resolve.rtt.us`
` monitor.duration.us`
Thank you.
---
### Author:  [@ashishtiwari1993](https://discuss.elastic.co/u/ashishtiwari1993)
#### Post date: [January 2, 2025, 3:11am UTC](https://discuss.elastic.co/t/field-documentation-for-icmp-tcp-and-http-synthetic-monitor/372674/2 "2025-01-02T03:11:34Z")
Hi @Yechezkal_Gutfreund Welcome to the Elastic community. Here is quick understanding from my side -
1. `icmp.rtt.us` : Measures the time (in microseconds, us) taken for an Internet Control Message Protocol (ICMP) packet (e.g., a ping) to travel to a destination and back to the source.
2. `resolve.rtt.us`: Measures the time (in microseconds, us) taken to resolve a domain name to an IP address using DNS.
3. ` monitor.duration.us`:Measures the total time (in microseconds, us) taken to complete the entire synthetic monitoring check, including all phases like DNS resolution, TCP connection, request/response etc.