Internet Standards and Services

12

Objectives

In this chapter, you will learn to:

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

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

Internet draft - a thorough explanation of a proposed standard.

Internet Engineering Steering Group (IESG) - a committee made of IETF technical area directors that oversees IETF decisions.

Request for Comments (RFC) - a numbered document that articulates some aspect of Internet technology.

Proposed standard - reclassified Internet draft.

Draft standard - a proposed standard that has been successfully by at least two independent researchers.

Technical Specifications

Technical Specifications

Address Assignments and Naming

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).

Regional Internet Registries (RIRS) - a not-for-profit agency that manages the distribution of IP addresses to private and public entities.

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

TCP/IP is a protocol suite that contains several subprotocols.

Some subprotocols, such as TCP, are connection-oriented.

Connectionless subprotocols do not guarantee data delivery, but can transmit data faster than connection-oriented subprotocols.

Every addressable computer connected to a TCP/IP network is known as a host.

Every host can take a host name, a name that describes the device.

Host and Domain Naming

Each host belongs to a domain, which also has a name.

Every host on a TCP/IP network requires a unique IP address to communicate with other hosts.

Each IP address is a unique 32-bit number, divided into four octets, or 8-bit bytes.

Host Files

Domain Name System (DNS)

A hierarchical way of identifying domain names and their addresses.

Relies on a database, which is distributed over key computers, known as root servers, across the Internet.

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

Name space - the database of Internet IP addresses and their associated names.

Resource Record - a single record that describes one piece of information in the DNS table.

Resolvers - any host on the Internet that need to look up domain name information and associate it with an IP address.

Name servers (DNS servers) - contain databases of names and their associated IP addresses.

The Use of Ports

The logical address on a host where an application makes itself available to incoming data.

The use of port numbers simplifies TCP/IP communications and ensures that data are transmitted to the correct application.

Port numbers can have any numeric value from 0 to 65536.

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, a connection to DNS servers, routers, Web server software, and a connection to the Internet

Hypertext Transfer Protocol (HTTP) and Hypertext Markup Language (HTML)

HTTP - operates at the Application layer of the TCP/IP model.

HTML - the Web document formatting language.

World Wide Web Consortium (W3C) - a standards organization for Web browsers and languages.

Tags - formatting indicators.

Hypertext Transfer Protocol (HTTP) and Hypertext Markup Language (HTML)

Uniform Resource Locators (URLs)

Simple Mail Transfer Protocol (SMTP)

Operates in the Application layer of the TCP/IP model and relies on TCP at the Transport layer.

Operates from TCP port 25.

SMTP is a simple subprotocol, incapable of doing anything more than transporting mail or holding it in a queue.

Post Office Protocol

Provides centralized storage for e-mail messages.

Users need an SMTP-compliant mail program to connect to their POP server and download mail from storage.

POP does not allow users to store mail on the server after they download it.

Internet Mail Access Protocol (IMAP)

Features: Users can retrieve all or only a portion of any mail message.

Users can review their messages and delete them while the messages remain on the server.

Users can create sophisticated methods of organizing messages on the server.

Users can share a mailbox in a central location.

IMAP4 can provide better security than POP because it supports authentication.

File Transfer Protocol (FTP)

FTP commands: 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

Provide a means of conveying messages

Distributed to a wide group of users at once rather than from user to another

Newsgroup messages are transported by the Network News Transfer Protocol (NNTP).

NNTP operates via TCP port 119.

Internet Telephony

Voice over IP (VoIP) - Breaks voice signals into packets and transmits them over data networks using UDP.

When Voice is carried over the Internet, it is also known as Internet telephony.

Intranets and Extranets

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.

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

The TCP/IP administration utility for use with Windows NT, 2000, XP, Vista, Windows 7 operating system.

Provides information about a NIC’s IP address, subnet mask, and default gateway.

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

Popular “switches”: ?: display a list of switches available for use with the

ipconfig command.

/all: displays complete TCP/IP configuration information for each network interface on that device.

/release - releases DHCP-assigned addresses for all of the device’s network interfaces.

/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.

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

Can be used to verify the network connectivity.

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.

Helpful in determing local connectivity problems.

Ping

Common “Switches”: -?: Displays the help text for the PING command, including its

syntax and a full list of switches.

-a: When used with an IP address, resolves the address to a host name.

-n: Allows you to specify a number of echo requests to send.

r: When used with a number from 1 to 9, displays the route taken during ping hops.

-w: Limits the time to wait for each echo response to a specific number of milliseconds.

Ping

Traceroute

Uses ICMP to trace the path from one host to another, identifying all intermediate hops between the two hosts.

Useful for determining router or network connectivity problems.

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.

Information that can be obtained include: 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

Common “switches”: -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

In 1969, the wide area network that became part of the Internet was known as ARPANET.

TCP/IP became the internet protocol after it was codified in 1972, designed to facilitate open communication between all computers.

DNS is a hierarchical means of identifying domain names and associated addresses.

THE END