Below are instructions explaining the details of the Interval, Interval Policy, and Verification Policy settings that are within the Web, TCP, and DNS check configurations.
1. Interval
Choose how often you want our monitoring nodes to check the status of your endpoint. Keep in mind, if you choose a shorter time, the more costly it will be. Also, consider that the more monitoring locations you choose will reduce the interval time if you choose the “Once per Site” or “Once per Region” interval policies.
Since we are running checks from multiple locations each interval, the interval period is actually reduced to Interval/Monitoring Locations and can be as short as a fraction of a second.
2. Interval Policy
Choose how many locations are checked at each check interval.
All Agents Per Interval - All selected agents will initiate a check but not simultaneously. The interval window will be divided by the number of agents, and all the agents will be checked within the interval. For example, if you have 2 selected agents with a 30-second interval, a check will run from all 2 agents but with a 15-second window apart from each other.
Things to consider when the first check runs:
1. If the first agent reports that the host is DOWN, the second agent configured will be checked on right away so we can get a decision on either the host is available or not.
2, If the first agent reports that the host is UP, we will trigger the second agent check after a 15-second window in this scenario.
One Agent Per Interval - A check will run from an individual agent at each check interval. For example, if you have 5 agents selected with a 30-second interval, one check will be run from one of the selected agents every 30 seconds.
One Agent Per Region Per Interval - A check will be run from one agent in all selected Regions per interval. For example, if you have 2 agents selected in all 6 regions with a 30-second interval, a check will be run from one agent in each selected region every 30 seconds. 
3. Verification Policy
Next, select a policy that will determine how agents will decide if a check is UP or Down.
Simple - When a monitoring node detects an endpoint as down, we will also check from a nearby location to verify. If the verification confirms the original report we will consider the check as Down.
Majority - Determine whether the check is UP or DOWN based on what the majority of the selected agents are reporting. Note: We recommend that you select at least 3 agents if you chose this option. 
Additionally, below are links to tutorials for specific check types: