Networking Protocols and Connectivity

Networking Protocols and Connectivity

Protocols

• Protocols govern how devices on the network interact and provide systems that allow data to travel reliably on the network.

• There are a number of commonly used protocols including TCP/IP, IPX/SPX, AppleTalk, and NetBEUI. Of these, TCP/IP is by far the most popular.

• In a TCP/IP network, the system requires at the very least an IP address and the subnet mask, and, in most cases, a default gateway, to get onto the network.

• DNS is a system that resolves host names to IP addresses. In order for a system to be able to send resolution requests to a DNS server, it must be supplied with the address of the DNS server. It is a common practice to supply the IP addresses of more than one DNS server.

• WINS is a service that resolves NetBIOS system names to IP addresses. WINS is commonly used on Microsoft networks but is now being replaced by DNS.

• TCP/IP information can be assigned manually, or dynamically using a DHCP server.

• Some operating systems (Windows 2000, Windows XP) support APIPA. If a system that is configured to use DHCP is unable to get an IP address from the DHCP server, APIPA will cause the system to assign itself an IP address, providing limited network functionality.

• IPX/SPX was created by the computer networking software company Novell. IPX/SPX is a suite of protocols designed primarily for use on local area networks (LANs).

• IPX/SPX has all but been replaced by TCP/IP and even Novell now uses TCP/IP as the default protocol in their networking products.

• AppleTalk is a networking protocol designed to be used on networks with Apple Macintosh computers.

• NetBEUI is a LAN protocol designed for relatively small networks. NetBEUI is simple to configure and easy to use.

• Configuring Client Options

  • Certain options must be configured on client systems in order for them to connect to the network correctly.

  • When connecting to a Microsoft network, clients need to know information such as the domain that the system is a member of and the correct user name and password.

  • When connecting to a Novell network, information such as the user name, the name of the NDS tree to which you want to connect, and the location of the user ID in tree (referred to as the context) is required.

• Ipconfig.exe

  • The Ipconfig command displays the TCP/IP configuration on Windows systems.

  • The most common command syntax used with the utility is ipconfig /all, which displays information on all network cards in the system including the default gateway, the subnet mask, the MAC address of the network card, DNS server information, and DHCP lease information.

  • Ipconfig can also be used to release and renew addresses obtained via DHCP.

• Winipcfg.exe

  • The Winipcfg utility is a graphical version of the Ipconfig utility found only in Windows 9x and Windows Me.

  • Winipcfg can report TCP/IP configuration information and can also be used to release and renew TCP/IP addresses obtained via DHCP.

• Ping

  • The Ping utility tests connectivity between networked devices that use the TCP/IP protocol.

• Tracert

  • Tracert verifies the route to a remote system by reporting the status of every step on the journey.

• Nslookup

  • The Nslookup utility can be used to troubleshoot the DNS configuration on a system.

Network Sharing

• Sharing Disk Drives

  • To share a hard disk drive, File and Printer Sharing must be enabled on the system.

  • To share a drive, right-click on the drive you wish to share and select Sharing from the menu.

  • Once a drive is shared, a hand will appear underneath the drive icon to let you know it is shared.

  • Access to shared drives over the network is controlled by permissions. Windows NT and Windows 2000/XP offer more share security that Windows 9x.

  • Shared drives can be accessed through My Computer, Network Neighborhood, and from the command line.

• Sharing Print and File Services

  • By default, Windows NT and Windows 2000 are configured to share resources.

  • In Windows 9x and Windows Me, File and Printer Sharing must first be installed and then you must specify that you wish to make files and/or printers available to other users.

  • You can map to a share on a network using the NetBIOS name or the IP address and the sharename in a UNC format.

• Setting Permissions to Shared Resources

  • Shared resources can be assigned permissions so that only intended users can gain access to them.

  • Windows NT and Windows 2000/XP provide four levels of share permissions—No Access, Read, Change, and Full Control.

  • Permissions assigned to a user and group can be combined to gain a greater set of rights, but the No Access permission cannot be overridden.

  • When you create a share, by default the Full Control permission is assigned to the group Everyone.

  • Permissions can be viewed and changed through Windows Explorer.

• Network Type and Network Card

  • Two types of networks are used, peer-to-peer and client/server networks.

  • In a peer-to-peer network, PCs can act as both a client and a server. As well as sharing their own resources, systems can be used to access other machines that make their own resources available.

  • Peer-to-peer networks are small, typically restricted to 10 computer systems.

  • Peer-to-peer networks do not use a dedicated network server.

  • Client/server networks use a dedicated server to manage network authentication, security, and access to network resources.

  • Client/server networks can accommodate thousands of interconnected systems.

  • The OS must have a network card installed and configured in order to connect to network resources. The network card provides the physical connection to the network.

  • The OS has to have a network protocol installed to communicate over the network.

Internet Concepts and Connectivity

• An ISP (Internet service provider) is a company that specializes in providing Internet access to home and business users. ISPs can provide different types of Internet access including dial-up phone access, cable access, and DSL.

• TCP/IP

  A protocol suite used by default by most operating systems and the protocol used on the Internet. TCP/IP information can be assigned manually (statically), or automatically using a DHCP server. Some of the protocols found within the TCP/IP protocol suite are included in Table B-7.

  Table B-7. TCP/IP Protocols and Their Functions

  Protocol	Function
  File Transfer Protocol (FTP)	FTP is used to send and receive files from a remote computer—for example, it can be used when downloading a program from the Internet.
  Hypertext Transfer Protocol (HTTP)	HTTP is used to establish a connection with a Web server and transmit HTML pages to the client browser.
  Hypertext Transfer Protocol Secure (HTTPS)	This protocol is used for accessing a secure Web server such as for online banking or other secure Internet transactions. Using HTTPS in the URL instead of HTTP directs the browser to establish a secure connection.
  Secure Sockets Layer (SSL)	SSL is the security system used by HTTPS. SSL works by encrypting information sent to and received from a remote host making it unreadable by a third party.
  Network News Transfer Protocol (NNTP)	This protocol is used to connect to, browse, and retrieve messages from newsgroups on the Internet. To connect to a news server, at the very least you will need the IP address of your ISP’s NNTP server.
  Post Office Protocol 3 (POP3)	POP3 is a single-user e-mail retrieval protocol, which allows a user to download e-mail from a remote mail host.
  Point-to-Point Protocol (PPP)	This is a dial-up networking protocol used to establish network connections over a modem link.
  Simple Mail Transfer Protocol (SMTP)	SMTP is used to send e-mail across a network such as the Internet.
  Internet Messaging Application Protocol (IMAP)	A protocol, like POP3, that is used for retrieving e-mail from a remote host. IMAP has more features than POP and is more secure.

• Telnet

  Telnet is a protocol that allows you to open a session on a remote host and perform actions through that session that are executed at the remote host as if you were actually at that host. Telnet is popular in the Linux/UNIX environment and for the configuration of network devices such as routers.

• HTML

  Tag language used to develop Web pages for the Internet. Web browsers interpret pages that are written in HTML and display the results in the browser window.

• DNS

  As discussed, the Domain Name Service is responsible for resolving host names to IP addresses. On the Internet, organizations are defined by their domain name and also by a domain name extension. Common domain name extensions are listed in Table B-8.

Table B-8. Common Domain Name Extensions

Extension	Purpose	Example
.com	Commercial business	www.microsoft.com
.org	Not-for-profit organizations	www.comptia.org
.edu	Educational organizations	www.harvard.edu
.gov	Government organizations	www.whitehouse.gov
.mil	Military organizations	www.nic.mil
.net	Internet organizations	www.att.net

Installing and Configuring Browsers

• Browsers are programs that are used to view pages formatted in certain languages such as the Hypertext Markup Language (HTML) or the Extensible Markup Language (XML).

• Internet Explorer is configured in the Internet Properties dialog box. Configurable options include connection method, LAN settings, security, home page, and privacy settings.

Internet Connectivity Technologies

• Dial-up Internet access, that is, access via a modem, is still the most popular method of connecting to the Internet. Dial-up networking is currently limited to 56 Kbps, making it slow in comparison to other Internet access methods such as DSL and cable.

• A dial-up connection to the Internet requires a modem and a special protocol called the Point-to-Point Protocol (PPP).

• Many methods of connecting to the Internet are available including cable, DSL, wireless, and satellite. Availability of these services depends on your location and the local ISP’s offerings. Most urban areas have DSL and cable Internet access, while satellite Internet access is gaining ground in rural areas where DSL and cable are not available.

• ISDN is a high-speed Internet access service that uses phone lines to provide speeds of up to 1.544 Mbps. There are two versions of ISDN—Basic Rate Interface (BRI), which is limited to 128 Kbps, and Primary Rate Interface (PRI), which is capable of the aforementioned 1.544 Mbps. By sacrificing some of the bandwidth on an ISDN line, you can also use voice traffic over the same link.

• Internet access across a LAN is becoming almost standard in networks of all sizes. When accessing the Internet across a LAN, specialized proxy server software is often used to manage and control Internet access.