RTT (Round Trip Time) is the time it takes to measure a round-trip from when a browser sends a request to a server and receives a response. One can safely call it a critical performance metric for web applications.
Along with Time to First Byte (TTFB), it's one of the two main factors used to measure page load times and network latency.
RTT is important when measuring the speed of your connection, and is commonly used by network administrators to diagnose the health of your network. Reducing RTT is one way we help improve your latency. RTT reduction is also a CDN's primary goal.
RTT is commonly used to measure the speed of connections for applications like gaming, video conferencing, or other online interactive applications. It's also used in measuring the speed of DNS queries and how long it takes to load images and other objects from your website.
Time To First Byte is a critical performance metric for web applications, that is the time it takes to receive the first byte of a response from a server. It is one of the two main factors used to measure page load times and network latency, along with Round Trip Time (RTT).
While RTT measures the total time it takes for a browser to receive data from a server, TTFB measures the time it takes for a browser to receive just the first byte of information about a website.
This is also commonly known as the "request phase" in a web request/response cycle.
A lower TTFB time will give users the impression of a faster loading site since there was less time between requesting the page and when it finished loading on their screen.
Lower TTFB time will also give slight ranking benefits since Google can place more importance on this metric when ranking search results. The combination of RTT and TTFB gives you a better idea about how long it will take to load your site compared to using either metric alone.
Most of the major operating systems provide users with a way to measure their own RTT:
tracert google.comand then hitting enter.
ping -o google.comand then hitting enter.
ping -c5 google.com.
RTTVAR (Round Trip Time Variation) is the variation in time it takes to receive a response from a server. Ideally, you want your RTT values to be consistent and low. The lower the better. RTT Variation will measure how much variation there is in the time it takes to receive a response from the same server. The higher the variance, the less consistent your connections to the server are.
There are several common ways of getting RTT values.One of the most popular is using Chrome DevTools or any other browser's developer tools, you can see the loading times for each object on the page, including images.