TTL (time to live) is the amount of time that your DNS record is cached in resolving name servers the Internet, measured in seconds. If your IP is dynamic (changes often) or if you plan to move your computer to another IP, it is recommended to set your TTL to a lower value to minimize this cache time. Once your IP is on a static IP or after you have transferred your system to the new IP, it is recommended to switch your TTL to a higher value.
The higher the TTL the faster the performance of DNS since most machines will have the value cached for a longer period of time reducing lookups. However, a TTL that it too high often causes lengthy periods of downtime if your system is ever needs to switch IPs.
If your computer's IP is static then a recommended TTL ranges from 12 hours (43200 seconds) to 24 hours (86400 seconds). If your computer uses a dynamic IP then it is recommended that your TTL is between 5 and 120 seconds.