1. DNS Conceptos Básicos

2. DNS – Conceptos Básicos Structure of Computer Names To obtain a domain, an organization must register with the Internetn autority. A unique domain suffix is assigned to each organization. mordred.cs.purdue.edu www.buknell.edu

3. DNS – Conceptos Básicos Geographic Structure Corporation For National Research Initiatives: cnri.reston.va.us Banco Nacional de Costa Rica: www.bncr.fi.cr

4. DNS – Conceptos Básicos Domain Names within Organization computer.foobar.com computer.location.foobar.com computer.division.location.foobar.com walnut.candy.foobar.com The number of segments in a domain corresponds to the naming hierarchy. There is no universal standard because each organization can choose how to structure names in its hierarchy. Futhermore, names within an organization do not need to follow a uniform pattern because individual groups within the organization can chosee a hierarchical structure that is appropriate for the group

5. DNS – Conceptos Básicos The DNS Client – Server Model Distribute Database The DNS Server Hierarchy Authority, Hierarchy Server Architectures Single Server, Update, Multiple Servers

6. DNS – Conceptos Básicos Locality Of Reference and Multiple Server The locality of reference principle: computer communication follows two distinct patters. Fist, a computer is more likely to communicate with computers that are physically nearly than with computers that are far away. Second, a computer is more likely to commmunicate with the same set of computers repeatedly. Pag 103, Cap 8, Comer

7. DNS – Conceptos Básicos Links Among Servers All domain name servers are linked together to form a unified system. Each server knows how to reach a root server and how to reach servers that are authorities for names further down the hierarchy

8. DNS – Conceptos Básicos Resolving a Name The translation of domain name into an equivalent IP address is called named resolution The resolver software in a host always request recursive resolution in which a name is resolved to an equivalent address. When it becomes a client of another server, a server can request iterative resolution to step trough yhe server hierarchy one level at a time

9. DNS – Conceptos Básicos Optimization of DNS Performance NS1.A NS2.A 1.A 2.A 3.A 1.A 2.A 3.A Replication:

10. DNS – Conceptos Básicos Optimization of DNS Performance DNS Caching is more important than replication because caching affects most of the system. A B C Client 1.C 2.C 1.C1.Z Z RED ?

11. DNS – Conceptos Básicos Types of DNS Entries The domain name system stores a type with each entry. When resolver looks up name, the resolver must specify the type that is desired; a DNS server retuns only entries that match the specified