Transcript TCP/IP: The Application Layers

Networking with TCP/IP
and the Application Layers
Sockets and Ports
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Socket
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Logical address assigned to a specific
process running on a host computer
The socket’s address combines the host
computer’s IP address with the port
number associated with a process
Port numbers in the range of 0 to 1023 are
called well-known ports
Sockets and Ports
Sockets and Ports
Host Names and Domain Name
System (DNS)
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Host name
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Symbolic name that describes a TCP/IP
device
Domain
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Group of computers that belong to the
same organization and have part of their IP
addresses in common
Domain Names
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Symbolic name that identifies an
organization
Top-level domains (TLDs)
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Highest-level category used to distinguish
domain names
A TLD is known as the domain suffix
Domain Names
Host Files
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Text file that associates TCP/IP host names with IP
addresses
Alias
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Nickname for a node’s host name
Domain Name System (DNS)
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Hierarchical way of tracking domain names and
their addresses, devised in the mid-1980s
Domain Name System (DNS)
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Resolvers
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Hosts on the Internet that need to look up
domain name information
Name servers
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Servers that contain databases of names and
their associated IP addresses
Each name server manages a group of device,
collectively known as a zone
Configuring DNS
DNS Name Space
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Name space
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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
Visit: http://www.icann.org/
And: http://www.newroot.com/rootservers.htm
DNS Name Space
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Resource record
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Element of a DNS database stored on a
name server that contains information
about TCP/IP host names and their
addresses
Address resource record
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Type of resource record that maps the IP
address of an Internet-connected device to its
domain name
Dynamic Host Configuration
Protocol (DHCP)
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Automated means of assigning a unique IP
address to every device on a network
Reasons for implementing DHCP
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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
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Lease
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Agreement between DHCP server and client on how long the
client will borrow a DHCP-assigned IP address
Terminating a DHCP Lease
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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
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The act of terminating a DHCP lease
Windows Internet Naming
Service (WINS)
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Provides a means of resolving NetBIOS
names with IP addresses
WINS offers several advantages
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Guarantees a unique NetBIOS name is
used for each computer on a network
Support for DHCP
Better network performance
Windows Internet Naming
Service (WINS)
Review of TCP/IP Subprotocols
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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)
Simple Mail Transfer Protocol
(SMTP)
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SMTP
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Responsible for moving messages from one
e-mail server to another
Internet Mail Access Protocol
(IMAP)
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Mail storage and manipulation protocol
that depends on SMTP’s transport
system
Hypertext Transport Protocol
(HTTP)
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Language that Web clients and servers use
to communicate
Forms the backbone of the Web
Hypertext Markup Language (HTML)
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Language that defines formatting standards
for Web documents
Hypertext Transport Protocol
(HTTP)
Network Time Protocol (NTP)
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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
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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
Packet Internet Groper (PING)
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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
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Netstat utility display TCP/IP statistics and details
about TCP/IP components and connections on a host
Nbstat
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The nbstat utility can provide information
about NetBIOS statistics and resolve
NetBIOS names to their IP addresses
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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
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Allows you to look up the DNS host name of a
network node by specifying its IP address, or vice
versa
Traceroute
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Uses ICMP to trace path from one networked node to another
Also known as tracert on Windows machines
Ipconfig
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TCP/IP administration utility for use with Windows NT and
Windows 2000 operating systems
Winipcfg
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This utility performs the same TCP/IP configuration
management as the ipconfig utility, but also applies to
Windows 9x and Me operating systems
Winipcfg
Internet Services
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World Wide Web (WWW, or Web)
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Collection of internetworked servers that share
resources and exchange information according
to specific protocols and formats
Browser
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Software that provides clients with a simple,
graphical interface to the Web
World Wide Web
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Uniform Resource Locator (URL)
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Standard means of identifying every
Web page
File Transfer Protocol (FTP)
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FTP - Manages files transfers between TCP/IP hosts
E-commerce
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E-commerce
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Means of conducting business over the Web