1. Anycast & dns
by SHAURYA RASTOGI

2. Root DNS Its is the top most DNS in the DNS hierarchy .
It contains entries of DNS nameservers all top level domains (TLD) i.e .com, .net, .org etc

3. Root DNS(contd) There are total 13 root nameservers from A to M
C,F,I,J,K,L,M nameservers are replicated around the world and use anycast to provide service

4. Anycast What is Anycasting ?
How is it different from Multicasting and Unicasting and Broadcasting ?

5. Unicast Broadcast Multicast Anycast

6. Anycasting in DNS
The Root DNS which uses anycast as service medium has multiple copies running around the world.
When a TLD DNS lookup is done, the request is delivered to the “nearest” Root DNS.

7. Anycast over BGP AS 2 AS 1 AS 3 AS 4 DNS Root: K DNS Root: K
AS 2
AS 2
AS 1
AS 1
AS 3
AS 3 AS 2
AS 4
AS 1

8. Benefits of Anycasting in DNS
Use of anycasting allows replication of single root DNS nameserver at multiple locations around the world.
It reduces the latency in case of DNS lookup from root DNS.
Reduce impact of DOS attacks.

9. Letter
IPv4 address
IPv6 address
Old name
Operator
Location A
2001:503:ba3e::2:30
ns.internic.net
VeriSign
Dulles, Virginia, U.S. B
2001:478:65::53
ns1.isi.edu
USC-ISI
Marina Del Rey, California, U.S. C
c.psi.net
Cogent Communications
distributed using anycast D
terp.umd.edu
University of Maryland
College Park, Maryland, U.S. E
ns.nasa.gov
NASA
Mountain View, California, U.S. F
2001:500:2f::f
ns.isc.org
ISC G
ns.nic.ddn.mil
Defense Information Systems Agency
Columbus, Ohio, U.S. H
2001:500:1::803f:235
aos.arl.army.mil
U.S. Army Research Lab
Aberdeen Proving Ground, Maryland, U.S. I
2001:7fe::53 (testing)
nic.nordu.net
Autonomica J
2001:503:C27::2:30 K
2001:7fd::1
RIPE NCC L
(since November 2007; was )
2001:500:3::42
ICANN M
2001:dc3::35
WIDE Project