# Base Attributes
A measurement definition contains a few base properties, and a myriad of type-specific options. For example, while all definitions have an af property, only traceroute measurements have a paris property.
# Base Properties
These properties are available for all measurement types.
| Name | Description | Default | Required? | Price Modifier |
|---|---|---|---|---|
| description | The name you give this measurement. | YES | ||
| af | The address family. Must be either 4 or 6. | YES | ||
| type | The type of measurement you're attempting to create. Must be one of: ping, traceroute, DNS, SSL or NTP. | YES | ||
| resolve_on_probe | Set to "true" if you want the probe to resolve your target instead of the RIPE Atlas servers. | false | ||
| skip_dns_check | Set to "true" if you want to create the measurement even if the RIPE Atlas servers can't resolve your target. | false | ||
| is_oneoff | Set this to "true" to make this measurement a one-off. | false | 2 | |
| start_time | Time when when this measurement must start | global start_time or now | ||
| stop_time | Time when when this measurement must stop | global stop_time or never | ||
| interval | In normal (not one-off) measurements, this value represents the number of seconds between measurements by a single probe. Note that while interval is defined for each measurement type, the default varies, so check the appropriate section below for the default values. | changes with type | ||
| spread | Distribution of probes' measurements throughout the interval. More info is here | half the interval, maximum 400 seconds | ||
| is_public | Make this measurement public, so other people can see the results. | true |