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Lecture TCP-IP protocol suite (3/e): Chapter 17 - Behrouz Forouzan

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Chapter 17 - Domain name system: DNS. After studying this chapter you will be able to: Understand how the DNS is organized, know the domains in the DNS, know how a name or address is resolved, be familiar with the query and response formats, understand the need for DDNS. | Chapter 17 Upon completion you will be able to: Domain Name System: DNS Understand how the DNS is organized Know the domains in the DNS Know how a name or address is resolved Be familiar with the query and response formats Understand the need for DDNS Objectives TCP/IP Protocol Suite 17.1 NAME SPACE The names assigned to machines must be unique because the addresses are unique. A name space that maps each address to a unique name can be organized in two ways: flat or hierarchical. The topics discussed in this section include: Flat Name Space Hierarchical Name Space TCP/IP Protocol Suite 17.2 DOMAIN NAME SPACE The domain name space is hierarchical in design. The names are defined in an inverted-tree structure with the root at the top. The tree can have 128 levels: level 0 (root) to level 127. The topics discussed in this section include: Label Domain Name Domain TCP/IP Protocol Suite Figure 17.1 Domain name space TCP/IP Protocol Suite Figure 17.2 Domain names and . | Chapter 17 Upon completion you will be able to: Domain Name System: DNS Understand how the DNS is organized Know the domains in the DNS Know how a name or address is resolved Be familiar with the query and response formats Understand the need for DDNS Objectives TCP/IP Protocol Suite 17.1 NAME SPACE The names assigned to machines must be unique because the addresses are unique. A name space that maps each address to a unique name can be organized in two ways: flat or hierarchical. The topics discussed in this section include: Flat Name Space Hierarchical Name Space TCP/IP Protocol Suite 17.2 DOMAIN NAME SPACE The domain name space is hierarchical in design. The names are defined in an inverted-tree structure with the root at the top. The tree can have 128 levels: level 0 (root) to level 127. The topics discussed in this section include: Label Domain Name Domain TCP/IP Protocol Suite Figure 17.1 Domain name space TCP/IP Protocol Suite Figure 17.2 Domain names and labels TCP/IP Protocol Suite Figure 17.3 FQDN and PQDN TCP/IP Protocol Suite Figure 17.4 Domains TCP/IP Protocol Suite 17.3 DISTRIBUTION OF NAME SPACE The information contained in the domain name space is distributed among many computers called DNS servers. The topics discussed in this section include: Hierarchy of Name Servers Zone Root Server Primary and Secondary Servers TCP/IP Protocol Suite Figure 17.5 Hierarchy of name servers TCP/IP Protocol Suite Figure 17.6 Zones and domains TCP/IP Protocol Suite A primary server loads all information from the disk file; the secondary server loads all information from the primary server. When the secondary downloads information from the primary, it is called zone transfer. Note: TCP/IP Protocol Suite 17.4 DNS IN THE INTERNET The domain name space (tree) is divided into three different sections: generic domains, country domains, and the inverse domain. The topics discussed in this section include: Generic Domains .