This delay in routers is what we called Packetization delay
or also called Accumulation delay. Packetization delay is the time required for
the information to pass on the wires. The data rate of the links that passes
thru the wires cause the delay.
Sandbox testing is used to test the new changes which is not their in your production server. Sandbox refers to a test server where we can deploy untested changes so that tester can test those changes separately
