15-441 Computer Networking Lecture 13-DNS
15-441 Computer Networking Lecture 13 – DNS
Outline DNS Design DNS Today Lecture13:10-10-2006
Lecture 13: 10-10-2006 2 Outline • DNS Design • DNS Today
Naming How do we efficiently locate resources? DNs:name→| P address Challenge How do we scale these to the wide area? Lecture13:10-10-2006 3
Lecture 13: 10-10-2006 3 Naming • How do we efficiently locate resources? • DNS: name → IP address • Challenge • How do we scale these to the wide area?
Obvious Solutions (1) Why not centralize dNs? Single point of failure · Traffic volume Distant centralized database Single point of update Doesnt scale Lecture13:10-10-2006
Lecture 13: 10-10-2006 4 Obvious Solutions (1) Why not centralize DNS? • Single point of failure • Traffic volume • Distant centralized database • Single point of update • Doesn’t scale!
Obvious Solutions (2) Why not use /etc/hosts? Original Name to Address Mapping Flat namespace letc/hosts SRI kept main copy Downloaded regularly Count of hosts was increasing machine per domain machine per user Many more downloads Many more updates Lecture13:10-10-2006 5
Lecture 13: 10-10-2006 5 Obvious Solutions (2) Why not use /etc/hosts? • Original Name to Address Mapping • Flat namespace • /etc/hosts • SRI kept main copy • Downloaded regularly • Count of hosts was increasing: machine per domain → machine per user • Many more downloads • Many more updates