[nylug-talk] 13 root-servers --> UDP datagram?

[alex at pilosoft.com]

On Mon, 11 Jun 2007, Raj Gurung wrote:

> Hi folks,
> 
> I am curious about the number of DNS root-servers. Is the UDP datagram
> size restricting the number of root-servers to 13 ?  If so, please light
> me up with ur knowledge. If not, what might be the cause ?
Let's clarify something.

There are far more than 13 *physical hosts*. However, there are 13
organizations running a "root server", each has a single IP address. Root
servers are distributed worldwide (as determined by said organization) via 
"udp anycast" (look that up).

The reason there are 13 is because that's all that's guaranteed to fit 
into a single 512-byte UDP packet.

see: www.root-servers.org for more info.