CIS 1140 Networking Fundamentals

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Chapter Eleven Networking with TCP/IP and the Internet

 

Objectives

Addressing and Name Resolution

IP Addressing

Static address

IP address that is manually assigned to a device

Dynamic address

IP address that is assigned to a device through DHCP

Dotted decimal notation

"Shorthand" convention used to represent IP addresses and make them more easily readable by people

 

Multicasting

Allows one device to send data to a specific group of devices (not the entire network segment)

New addressing scheme is being developed

IP version 6 (IPV6) will incorporate this new scheme

Subnetting

Process of subdividing a single class of network into multiple, smaller networks

Extended network prefix

The combination of an address’s network and subnet information

Subnet mask

Special 32-bit number that, when combined with a device’s IP address, informs the rest of the network about the network class to which the device is on

Gateways

Core Gateways

Gateways that make up the Internet backbone

Gateways Network Address Translation (NAT)

Technique in which IP addresses are assigned a public IP address by an IP gateway

Sockets and Ports

Socket

Host Names and Domain Name System (DNS)

Host name

Symbolic name that describes a TCP/IP device

Domain

Group of computers that belong to the same organization and have part of their IP addresses in common

Domain Names

Highest-level category used to distinguish domain names

A TLD is known as the domain suffix

Host Files

Text file that associates TCP/IP host names with IP addresses

Alias

Nickname for a node’s host name

On a UNIX-based computer a host file is:

Called hosts

Located in the /etc directory

On a Windows 9x computer, a host file:

Is called lmhosts

Must be located in the c:\windows directory in order to be recognized by the operating system

Hierarchical way of tracking domain names and their addresses, devised in the mid-1980s

Resolvers

Hosts on the Internet that need to look up domain name information

Name servers

Servers that contain databases of names and their associated IP addresses

Each name server manages a group of device, collectively known as a zone

Name space

Refers to the actual database of Internet IP addresses and their associated names

Every name server holds a piece of the DNS name space

At the highest level of the hierarchy sit the root servers

Resource record

Element of a DNS database stored on a name server that contains information about TCP/IP host names and their addresses

Address resource record

Type of resource record that maps the IP address of an Internet-connected device to its domain name

Bootstrap Protocol (BOOTP)

Service that simplifies IP address management

Thanks to BOOTP, a client does not have to remember its own IP address

Therefore, network administrators do not have to go to each workstation on a network and manually assign its IP address

This situation is ideal for diskless workstations

Dynamic Host Configuration Protocol (DHCP)

Automated means of assigning a unique IP address to every device on a network

Reasons for implementing DHCP

Reduce the time and planning spent on IP address management

Reduce the potential for errors in assigning IP addresses

Enable users to move their workstations and printers without having to change their TCP/IP configuration

Make IP addressing transparent for mobile users

DHCP Leasing Process

Lease

Agreement between DHCP server and client on how long the client will borrow a DHCP-assigned IP address

Terminating a DHCP Lease

A DHCP lease may expire based on the period established for it in the server configuration

A DHCP lease may be manually terminated at any time from either the client’s TCP/IP configuration or the server’s DHCP configuration

In some instances, a user must terminate a lease

Release

The act of terminating a DHCP lease

Windows Internet Naming Service (WINS)

Provides a means of resolving NetBIOS names with IP addresses

WINS offers several advantages

Guarantees a unique NetBIOS name is used for each computer on a network

Support for DHCP

Better network performance

 

Addressing in IPv6

IPv6

Also known as IP next generation or IPng

Slated to replace the current IP protocol, IPv4

Perhaps the most valuable advantage IPv6 offers over IPv4 is its promise of billions and billions of additional IP addresses through its new addressing scheme

Unicast address

Type of IPv6 address that represents a single interface on a device

Multicast address

Type of address in IPv6 that represents multiple interfaces, often on multiple nodes

Anycast address

Type of address specified in IPv6 that represents a group of interfaces, any of which can accept a transmission

Another significant difference between IPv4 and IPv6 is that in IPv6, each address contains a Format Prefix

The Format Prefix is a variable-length field at the beginning of the address that indicates what type of address it is

The Format Prefix also establishes the arrangement of the rest of the address’s fields

Review of TCP/IP Subprotocols

Internet Protocol (IP)

Transport Control Protocol (TCP)

User Datagram Protocol (UDP)

Internet Control Message Protocol (ICMP)

Address Resolution Protocol (ARP)

Telnet

File Transfer Protocol (FTP)

Simple Network Management Protocol (SNMP)

Reverse Address Resolution Protocol (RARP)

Allows the client to send a broadcast message with the MAC address of a device and receive the device’s IP address in reply

Simple Mail Transfer Protocol(SMTP) and Post Office Protocol (POP)

SMTP

Responsible for moving messages from one e-mail server to another

POP

Provides centralized storage for e-mail messages

Internet Mail Access Protocol (IMAP)

Mail storage and manipulation protocol that depends on SMTP’s transport system

Developed as a more sophisticated alternative to POP

Most current version is version 4 (IMAP4)

Biggest advantage of IMAP4 over POP relates to the fact users can store messages on the mail server

Additional Features of IMAP4

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

Hypertext Transport Protocol (HTTP)

Language that Web clients and servers use to communicate

Forms the backbone of the Web

Hypertext Markup Language (HTML)

Language that defines formatting standards for Web documents

Network Time Protocol (NTP)

Used to synchronize the clocks of a computers on a network

Very simple protocol

Belongs to Application Layer of TCP/IP Model

Depends on UDP

TCP/IP Troubleshooting

Of all network protocols, TCP/IP is most likely to cause problems because it requires the most planning and post-installation configuration

Be aware of the troubleshooting tools and their switches

These troubleshooting utilities can be accessed from the command prompt on a server or client running TCP/IP

ARP

ARP table

Database that lists the associated MAC and IP addresses

Contains two types of entries:

Dynamic ARP table entries

Static ARP table entries

ARP utility provides a way of obtaining information from and manipulating a device’s ARP table

Packet Internet Groper (PING)

Troubleshooting utility that can verify TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network

An echo request is a signal sent out to another computer

An echo reply is the other computer’s response signal

Process of sending this signal back and forth is known as pinging

Netstat

Netstat utility display TCP/IP statistics and details about TCP/IP components and connections on a host

Nbstat

The nbstat utility can provide information about NetBIOS statistics and resolve NetBIOS names to their IP addresses

In other words, if you know the NetBIOS name of a workstation, you can use nbstat to determine its IP address

Nbstat is useful on networks that run Windows-based operating systems and NetBIOS

Nslookup

Allows you to look up the DNS host name of a network node by specifying its IP address, or vice versa

Traceroute

Uses ICMP to trace path from one networked node to another

Also known as tracert on Windows machines

Ipconfig

TCP/IP administration utility for use with Windows NT and Windows 2000 operating systems

Winipcfg

This utility performs the same TCP/IP configuration management as the ipconfig utility, but also applies to Windows 9x and Me operating systems

Ifconfig

TCP/IP configuration and management utility used on UNIX systems

Internet Services

World Wide Web (WWW, or Web)

Collection of internetworked servers that share resources and exchange information according to specific protocols and formats

Browser

Software that provides clients with a simple, graphical interface to the Web

World Wide Web

Uniform Resource Locator (URL)

Standard means of identifying every Web page

Unqualified host name

Host name minus its prefix and suffix

E-mail and File Transfer Protocol (FTP)

E-mail

Currently, e-mail is most relied-upon Internet service you will manage

FTP

Manages files transfers between TCP/IP hosts

Trivial File Transfer Protocol (TFTP) and Gopher

TFTP

TCP/IP Application layer protocol that enables file transfers between computers

Gopher

Text-based utility that allows you to navigate through a series of menus to find and read specific files

Newsgroups and E-commerce

Newsgroups

Provides means of conveying messages in which information is distributed to a wide group of users at once

Network News Transfer Protocol (NNTP)

Supports process of reading newsgroup messages, posting new messages, and transferring news files between news servers

E-commerce

Means of conducting business over the Web

Voice Over IP (VoIP)

Provision of telephone service over the Internet

Often called Internet telephony

Not all VoIP calls are carried over the Internet

VoIP over private lines is a very effective and economical method of completing calls between two locations within an organization

Voice Over IP (VoIP): Phone-to-Phone

Two traditional phones are connected through a TCP/IP network

One end of the call uses a PC, while the other end relies on a traditional telephone

Voice Over IP (VoIP): PC-to-PC

Two PCs connect through a TCP/IP network to complete calls

Chapter Summary

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