This article will explain what TTL is, and how it affects your domain names.
TTL stands for Time To Live, and measures the lifespan of data in a computer or network, for example, when you create an SRV record for your domain name. This dictates the length of time it takes for the cache of the server to update, so if you make a change, this is the length of time it will take the propagate. TTL is measured in seconds, so if you want to set a TTL of one hour, you would set the TTL to 3600 seconds.
When you create records for your domain names, the TTL is automatically set at 86400 seconds, which is 24 hours.