Curso: Redes y comunicaciones I: 07 Redes. Fue dictado en la Universidad Tecnológica del Perú -UTP, Lima - Perú, en los ciclos 2011-2 (junio/2011), 2011-3 (octubre/2011) y 2012-1 (abril/2012).

1. Semana 13
Redes
Redes y Comunicaciones I
Ingeniería de Telecomunicaciones
Facultad de Ingeniería de Telecomunicaciones y Telemática
Universidad Tecnológica del Perú
Ing. CIP Jack Daniel Cáceres Meza Septiembre 2011

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Domain Name System -DNS
 RFC 1035 (1987)
 Actualizaciones: 882, 883, 973, 1034, 4033, 4035
 Puerto: 53
 The goal of domain names is to provide a mechanism for naming
resources in such a way that the names are usable in different
hosts, networks,protocol families, internets, and administrative
organizations. From the user's point of view, domain names are
useful as arguments to a local agent, called a resolver, which
retrieves information associated with the domain name. Thus a
user might ask for the host address or mail information
associated with a particular domain name. To enable the user to
request a particular type of information, an appropriate query
type is passed to the resolver with the domain name. To the user,
the domain tree is a single information space; the resolver is
responsible for hiding the distribution of data among name
servers from the user.

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DNS Domain Namespace
Jerarquía
Delegación

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Types of DNS Domain Names
Name Type Description Example
Root domain
This is the top of the tree. When used in a DNS
domain name, it is stated by a trailing period (.)
to designate that the name is located at the root
or highest level of the domain hierarchy. In this
instance, the DNS domain name is considered
to be complete and points to an exact location
in the tree of names. Names stated this way
are called fully qualified domain names
(FQDNs).
A single period (.) or a
period used at the end of a
name, such as
“example.microsoft.com.”
Top level
domain
A name used to indicate a country/region or the
type of organization using a name.
““.com”, which indicates a
name registered to a
business for commercial
use on the Internet.
Second level
domain
Variable-length names registered to an
individual or organization for use on the
Internet. These names are always based upon
an appropriate top-level domain, depending on
the type of organization or geographic location
where a name is used.
““microsoft.com. ”, which is
the second-level domain
name registered to
Microsoft by the Internet
DNS domain name
registrar.

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Types of DNS Domain Names
Name Type Description Example
Subdomain
Additional names that an organization
can create that are derived from the
registered second-level domain
name. These include names added to
grow the DNS tree of names in an
organization and divide it into
departments or geographic locations.
““example.microsoft.com. ”, which is
a fictitious subdomain assigned by
Microsoft for use in documentation
example names.
Host or
resource
name
Names that represent a leaf in the
DNS tree of names and identify a
specific resource. Typically, the
leftmost label of a DNS domain name
identifies a specific computer on the
network. For example, if a name at
this level is used in a host (A) RR, it
is used to look up the IP address of
computer based on its host name.
““host-a.example.microsoft.com.”,
where the first label (“host-a”) is the
DNS host name for a specific
computer on the network.

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Description Class Time To Live (TTL) Type Data
Start of
Authority
Internet
(IN)
Default TTL is 60
minutes
SOA
Owner Name
Primary Name Server DNS
Name, Serial Number
Refresh Interval
Retry Interval
Expire Time
Minimum TTL
Host
Internet
(IN)
Record-specific TTL if
present, or else zone
(SOA) TTL
A
Owner Name (Host DNS
Name)
Host IP Address
Name Server
Internet
(IN)
Record-specific TTL if
present, or else zone
(SOA) TTL
NS
Owner Name
Name Server DNS Name
Mail
Exchanger
Internet
(IN)
Record-specific TTL if
present, or else zone
(SOA) TTL
MX
Owner Name
Mail Exchange Server DNS
Name, Preference Number
Canonical
Name
(an alias)
Internet
(IN)
Record-specific TTL if
present, or else zone
(SOA) TTL
CNAME
Owner Name (Alias Name)
Host DNS Name
Common DNS Resource Records
http://www.iana.org/assignments/dns-parameters

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Modelo de funcionamiento
whois

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Ejemplo de funcionamiento

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Tablas DNS -partial zone for physics department
Remember
named.conf
file
32 bit time interval,
in seconds
32 bit unsignedYYYYMMDDNNN
-formatted number

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Tablas DNS -glue records for physics department

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Tablas DNS -in-addr.arpa records
Subnet 12
Network 149.76

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Modelo de red actual

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Conmutación de circuitos

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Conmutación de paquetes

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HDSL
SHDSLADSL, ADSL2+
VDSL
Satélite
812.11 WiFi / WiMesh
PONSONET / SDH
HFC
SDV
812.16 WiMAX
WLL / WIpLL
(FTTH)
Coaxial
& Fibra
Par
trenzado
Wireless
Fibra
Óptica
Alternativas de Acceso Banda Ancha

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Wi-FI
 802.11a - 54 Mbps standard, 5 GHz signaling (ratified 1999), usado en ambientes comerciales, poca distancia,
frecuencia regulada
 802.11b - 11 Mbps standard, 2.4 GHz signaling (1999), usado en ambientes domésticos, propenso a interferencias,
frecuencia no regulada
 802.11c - operation of bridge connections (moved to 802.1D)
 802.11d - worldwide compliance with regulations for use of wireless signal spectrum (2001)
 802.11e - Quality of Service (QoS) support (not yet ratified)
 802.11F - Inter-Access Point Protocol recommendation for communication between access points to support roaming
clients (2003)
 802.11g - 54 Mbps standard, 2.4 GHz signaling (2003), buen rango de señal, poco propenso a obstrucción, propenso a
interferencias en frecuencia no regulada
 802.11h - enhanced version of 802.11a to support European regulatory requirements (2003)
 802.11i - security improvements for the 802.11 family (2004)
 802.11j - enhancements to 5 GHz signaling to support Japan regulatory requirements (2004)
 802.11k - WLAN system management (in progress)
 802.11m - maintenance of 802.11 family documentation
 802.11n - 100+ Mbps standard improvements over 802.11g (in progress) , más resistente a interferencias
 802.11p - Wireless Access for the Vehicular Environment
 802.11r - fast roaming support via Basic Service Set transitions
 802.11s - ESS mesh networking for access points
 802.11T - Wireless Performance Prediction - recommendation for testing standards and metrics
 802.11u - internetworking with 3G / cellular and other forms of external networks
 802.11v - wireless network management / device configuration
 802.11w - Protected Management Frames security enhancement
 802.11y - Contention Based Protocol for interference avoidance

17. Ing. CIP Jack Daniel Cáceres Meza
jack_caceres@hotmail.com
Gracias por su atención
¿Preguntas?