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

[Ron Guerin]

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 ?

To prevent fragmentation of UDP packets, DNS packets are limited to 512
bytes.

  2.3.4. Size limits

  Various objects and parameters in the DNS have size limits.  They
  are listed below.  Some could be easily changed, others are more
  fundamental.

  labels         63 octets or less
  names          255 octets or less
  TTL            positive values of a signed 32 bit number.
  UDP messages   512 octets or less

http://www.ietf.org/rfc/rfc1035.txt

- Ron