1. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Chapter 25 Domain Name System

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.1 Name Space Flat Name Space Hierarchical Name Space

3. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.2 Domain Name Space Label Domain Name

4. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.1 Domain name space

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.2 Domain names and labels

6. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.6 DNS Messages Header Question Section Answer Section Authoritative Section Additional Information Section

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.3 FQDN and PQDN

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.4 Domains

9. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.3 Distribution of Name Spaces Hierarchy of Name Servers Zone Root Server Primary and Secondary Servers

10. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.5 Hierarchy of name servers

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.6 Zones and domains

12. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 A primary server loads all information from the disk file; the secondary server loads all information from the primary server. Note:

13. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.4 DNS In The Internet Generic Domain Country Domain Inverse Domain

14. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.7 DNS in the Internet

15. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.8 Generic domains

16. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 25.1 Generic domain labels LabelDescription comCommercial organizations eduEducational institutions govGovernment institutions intInternational organizations milMilitary groups netNetwork support centers orgNonprofit organizations

17. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 25.2 New generic domain labels LabelDescription aeroAirlines and aerospace companies bizBusinesses or firms (similar to com) coopCooperative business organizations infoInformation service providers museumMuseums and other nonprofit organizations namePersonal names (individuals) proProfessional individual organizations

18. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.9 Country domains

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.10 Inverse domain

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 25.5 Resolution Resolver Mapping Addresses to Names Recursive Resolution Iterative Resolution Caching Mapping Names to Addresses

21. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.11 Recursive resolution

22. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.12 Iterative resolution

23. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.13 Query and response messages

24. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 25.14 Header format

25. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 DNS can use the services of UDP or TCP, using the well-known port 53. Note: