9.1 Figure Composed naming domains used to access a resource from a UR
URL http://www.cdk3.net:8888/WebExamples/earth.html DNS lookup Resource ID (IP number, port number, pathname) 55.55.55.55 8888 WebExamples/earth.html
Web server Network address 2:60:8c:2:b0:5a Socket
Instructor's Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Addison-Wesley Publishers 2000
file
Figure 9.2 Iterative navigation
NS2 2 Client 1 3 NS3 NS1
Name servers
A client iteratively contacts name servers NS1NS3 in order to resolve a name
Instructor's Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Addison-Wesley Publishers 2000
Figure 9.3 Non-recursive and recursive server-controlled navigation
NS2 2 1 client 4 NS1 3 NS3 client 1 5 NS1 2 4
NS2
3
NS3
Non-recursive server-controlled
Recursive server-controlled
A name server NS1 communicates with other name servers on behalf of a client
Instructor's Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Addison-Wesley Publishers 2000
Figure 9.4 DNS name servers
Note: Name server names are in italics, and the corresponding domains in are parentheses. Arrows denote name server entries ns1.nic.uk (uk) co.uk ac.uk ns0.ja.net (ac.uk) ic.ac.uk qmw.ac.uk a.root-servers.net (root) uk purdue.edu yahoo.com ns.purdue.edu (purdue.edu)
* .purdue.edu
dcs.qmw.ac.uk *.qmw.ac.uk alpha.qmw.ac.uk (qmw.ac.uk)
*.dcs.qmw.ac.uk
*.ic.ac.uk
dns0.dcs.qmw.ac.uk (dcs.qmw.ac.uk)
dns0-doc.ic.ac.uk (ic.ac.uk)
Instructor's Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Addison-Wesley Publishers 2000
Figure 9.5 DNS resource records
Record type Meaning
A NS CNAME SOA WKS PTR HINFO MX TXT A computer address An authoritative name server The canonical name for an alias Marks the start of data for a zone A well-known s...