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. UnicastBroadcast MulticastAnycast

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. AS 1 AS 3 AS 2 AS 4 193.0.14.129 193.0.14.129 193.0.14.129 AS 3 AS 2 193.0.14.129 AS 1 DNS Root: K 193.0.14.129 AS 2 Anycast over BGP 193.0.14.129 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. LetterIPv4 addressIPv6 addressOld nameOperatorLocation A198.41.0.42001:503:ba3e::2:30ns.internic.netVeriSignDulles, Virginia, U.S. B192.228.79.2012001:478:65::53ns1.isi.eduUSC-ISI Marina Del Rey, California, U.S. C192.33.4.12c.psi.net Cogent Communications distributed using anycast D128.8.10.90terp.umd.eduUniversity of Maryland College Park, Maryland, U.S. E192.203.230.10ns.nasa.govNASA Mountain View, California, U.S. F192.5.5.2412001:500:2f::fns.isc.orgISC distributed using anycast G192.112.36.4ns.nic.ddn.mil Defense Information Systems Agency Columbus, Ohio, U.S. H128.63.2.53 2001:500:1::803f:23 5 aos.arl.army.mil U.S. Army Research Lab Aberdeen Proving Ground, Maryland, U.S. I192.36.148.172001:7fe::53 (testing)nic.nordu.netAutonomica distributed using anycast J192.58.128.302001:503:C27::2:30VeriSign distributed using anycast K193.0.14.1292001:7fd::1RIPE NCC distributed using anycast L 199.7.83.42 (since November 2007; was 198.32.64.12) 2001:500:3::42ICANN distributed using anycast M202.12.27.332001:dc3::35WIDE Project distributed using anycast