Transcript ch 12 Internet Standards and Services

Internet Standards
and Services
12
Objectives
In this chapter, you will learn to:
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Summarize the history of today’s Internet
Identify the organizations that cooperate to set Internet
standards
Explain conventions for Internet domain and host naming
Describe several popular Internet-based services and
identify the protocols on which they rely
Run and interpret the output of simple TCP/IP-based
utilities
The Evolution of the Internet
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Advanced Research Projects Agency (ARPA) - an organization
formed by the United States government in 1958 to investigate and
develop new military defense technology.
ARPANET - a network that relied on telephone lines to transmit
messages that had been fragmented into small packages of data
between computers.
Domain Name System (DNS) - a formal, centralized method for
automatically associating IP addresses with host names.
NSFNET - supercomputing centers at five universities across the
nation plus a backbone to connect them with each other and, with other
organizations.
World Wide Web (WWW) - a collection of multiple Internet servers and
a method for organizing data scattered over these servers.
Technical Specifications
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Internet draft - a thorough explanation of a proposed standard.
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Internet Engineering Steering Group (IESG) - a committee
made of IETF technical area directors that oversees IETF
decisions.
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Request for Comments (RFC) - a numbered document that
articulates some aspect of Internet technology.
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Proposed standard - reclassified Internet draft.
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Draft standard - a proposed standard that has been
successfully by at least two independent researchers.
Technical Specifications
Technical Specifications
Address Assignments and Naming
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Internet Assigned Numbers Authority (IANA):
 kept records of available and reserved IP addresses.
 was also responsible for allocating domain names and
maintaining the Domain Name System (DNS).
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Regional Internet Registries (RIRS) - a not-for-profit agency
that manages the distribution of IP addresses to private and
public entities.
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Internet Corporation for Assigned Names and Numbers
(ICANN) - a private nonprofit corporation that is contracted by
the government to oversee IP addresses and domain name
management, plus accomplish specific Internet management
improvements.
Host and Domain Naming
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TCP/IP is a protocol suite that contains several subprotocols.
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Some subprotocols, such as TCP, are connection-oriented.
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Connectionless subprotocols do not guarantee data delivery, but
can transmit data faster than connection-oriented subprotocols.
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Every addressable computer connected to a TCP/IP network is
known as a host.
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Every host can take a host name, a name that describes the
device.
Host and Domain Naming
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Each host belongs to a domain, which also has a name.
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Every host on a TCP/IP network requires a unique IP
address to communicate with other hosts.
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Each IP address is a unique 32-bit number, divided into
four octets, or 8-bit bytes.
Host Files
Domain Name System (DNS)
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A hierarchical way of identifying domain names and their
addresses.
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Relies on a database, which is distributed over key
computers, known as root servers, across the Internet.
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The last label in a domain name represents a top-level
domain (TLD), or the highest level in a DNS hierarchy.
 For example, in the www.fcc.gov domain, the TLD is
“gov.”
Domain Name System (DNS)
Name Servers and Space
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Name space - the database of Internet IP addresses and
their associated names.
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Resource Record - a single record that describes one
piece of information in the DNS table.
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Resolvers - any host on the Internet that need to look up
domain name information and associate it with an IP
address.
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Name servers (DNS servers) - contain databases of
names and their associated IP addresses.
The Use of Ports
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The logical address on a host where an application
makes itself available to incoming data.
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The use of port numbers simplifies TCP/IP
communications and ensures that data are transmitted to
the correct application.
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Port numbers can have any numeric value from 0 to
65536.
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Port numbers in the range of 0 through 1023 are referred
to as well known port numbers.
The Use of Ports
World Wide Web (WWW)
On the client side, access to the Web requires: TCP/IP,
 a unique IP address,
 a connection to the Internet, and
 a browser
On the server side, a Web site requires TCP/IP,
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a connection to DNS servers,
routers,
Web server software, and
a connection to the Internet
Hypertext Transfer Protocol (HTTP)
and Hypertext Markup Language
(HTML)
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HTTP - operates at the Application layer of the TCP/IP
model.
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HTML - the Web document formatting language.
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World Wide Web Consortium (W3C) - a standards
organization for Web browsers and languages.
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Tags - formatting indicators.
Hypertext Transfer Protocol (HTTP) and
Hypertext Markup Language (HTML)
Uniform Resource Locators (URLs)
Simple Mail Transfer Protocol
(SMTP)
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Operates in the Application layer of the TCP/IP
model and relies on TCP at the Transport layer.
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Operates from TCP port 25.
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SMTP is a simple subprotocol, incapable of
doing anything more than transporting mail or
holding it in a queue.
Post Office Protocol
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Provides centralized storage for e-mail
messages.
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Users need an SMTP-compliant mail program
to connect to their POP server and download
mail from storage.
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POP does not allow users to store mail on the
server after they download it.
Internet Mail Access Protocol
(IMAP)
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Features:
 Users can retrieve all or only a portion of any mail message.
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Users can review their messages and delete them while the
messages remain on the server.
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Users can create sophisticated methods of organizing
messages on the server.
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Users can share a mailbox in a central location.
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IMAP4 can provide better security than POP because it
supports authentication.
File Transfer Protocol (FTP)
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FTP commands:
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ascii: Sets the file transfer mode to “ASCII.”
binary: Sets the file transfer mode to “binary.”
cd: Changes your working directory on the host machine.
delete: Deletes a file on the host machine
get: Transfers a file from the host machine to the client.
help: Provides a list of commands when issued from the
FTP prompt.
ls: Lists the contents of the directory on the host where you
are currently located.
mkdir: - Creates a new directory on the FTP host.
open: Creates a connection with an FTP host.
FTP
Newsgroups
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Provide a means of conveying messages
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Distributed to a wide group of users at once
rather than from user to another
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Newsgroup messages are transported by the
Network News Transfer Protocol (NNTP).
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NNTP operates via TCP port 119.
Internet Telephony
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Voice over IP (VoIP) - Breaks voice signals
into packets and transmits them over data
networks using UDP.
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When Voice is carried over the Internet, it is
also known as Internet telephony.
Intranets and Extranets
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Intranet - a network or part of a network that uses
Internet like services and protocols to exchange
information within an enterprise.
 Also used for e-mail, file sharing, document
management, and collaboration.
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Extranet - a network that uses Internet-like services and
protocol to exchange information over a broad
geographical area.
 Encompasses dedicated connections to multiple
offices within a company.
Ipconfig
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The TCP/IP administration utility for use with
Windows NT, 2000, XP, Vista, Windows 7
operating system.
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Provides information about a NIC’s IP address,
subnet mask, and default gateway.
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Can be used with “switches” to manage a
computer’s TCP/IP settings, including your
MAC address and the address of your WINS
server.
Ipconfig
Ipconfig
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Popular “switches”:
 ?: display a list of switches available for use with the
ipconfig command.
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/all: displays complete TCP/IP configuration
information for each network interface on that device.
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/release - releases DHCP-assigned addresses for all
of the device’s network interfaces.
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/renew - renews DHCP-assigned addresses for all of
the device’s network interfaces.
Ifconfig
The TCP/IP configuration and management
utility used on UNIX systems.
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Popular “switches”:
 -a: Applies the command to all interfaces on a device.
 down: Marks the interface as unavailable to the
network.
 -up: Reinitializes the interface after it has been taken
“down,” so that it is once again available to the
network.
Ifconfig
Ping
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Can be used to verify the network connectivity.
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Relies on the Internet control Message Protocol
(ICMP), which is a TCP/IP protocol that can be
used to detect that the transmission of packets
were delivered or not delivered.
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Helpful in determing local connectivity
problems.
Ping
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Common “Switches”:
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-?: Displays the help text for the PING command, including its
syntax and a full list of switches.
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-a: When used with an IP address, resolves the address to a host
name.
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-n: Allows you to specify a number of echo requests to send.
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r: When used with a number from 1 to 9, displays the route taken
during ping hops.
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-w: Limits the time to wait for each echo response to a specific
number of milliseconds.
Ping
Traceroute
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Uses ICMP to trace the path from one host to another,
identifying all intermediate hops between the two hosts.
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Useful for determining router or network connectivity
problems.
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Common “switches”:
 -d: Instructs the tracert command not to resolve IP
addresses to host names.
 -h: Specifies the maximum number of hops the
packets should take when attempting to reach a host.
 -w: Identifies a timeout period for responses.
Traceroute
Netstat
Displays TCP/IP statistics and details about
TCP/IP components and connections on a host.
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Information that can be obtained include:
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the port on which a particular TCP/IP service is running.
whether or not a remote node is logged on to a host.
which network connections are already established for a
client.
how many packets have been handled by a network
interface since it was activated.
How many data errors have occurred on a particular
network interface.
Netstat
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Common “switches”:
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-a: Provides a listing of all available TCP and UDP
connections, even if they are simply listening and not
currently exchanging data.
-e: Displays details about all the packets that have been
sent over a network interface.
-n: Lists currently connected hosts according to their port
and IP address.
-p: Allows you to specify what type of protocol statistics to
list.
-R: Provides a list of routing table information.
-S: Provides statistics about each packet transmitted by a
host, separated according to protocol type.
Summary
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In 1969, the wide area network that became part of the
Internet was known as ARPANET.
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TCP/IP became the internet protocol after it was codified
in 1972, designed to facilitate open communication
between all computers.
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DNS is a hierarchical means of identifying domain names
and associated addresses.
THE END