Reason for Limited number of Root DNS Servers

Gaurav Kansal gaurav.kansal at
Fri Nov 11 05:38:31 UTC 2011

Dear All,


Somewhere I read that number of ROOT DNS servers is limited to 13 because of
protocol limitation of DNS and UDP.

Exact writing was  "A combination of limits in the DNS and certain
protocols, namely the practical size of unfragmented User Datagram Protocol
(UDP) packets, resulted in a limited number of root server addresses that
can be accommodated in DNS name query responses. This limit has determined
the number of name server installations at (currently) 13 clusters, serving
the needs of the entire public Internet worldwide."


As root DNS are running in anycast so number is not an issue at all. But I
don't understand where exactly is this limitation exists???


Please some elaborate on this.



Thanks and Regards,

Gaurav Kansal



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