You are probably talking about VMs - those do have traffic limits. Servers, on the other side, with default 1Gbit NICs doesn't (let's say until you consume 80%+ of bandwidth for months)
Quoting:
> Traffic
>All root servers have a dedicated 1 GBit uplink by default and with it unlimited traffic. Inclusive monthly traffic for servers with 10G uplink is 20TB. There is no bandwidth limitation. We will charge € 1 ($1.20)/TB for overusage.
