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

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

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

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

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

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

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

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

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

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

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

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:

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

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

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

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

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

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

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

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

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

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

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

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

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