Exam Essentials ( Network+ Chapter 3 )

Exam Essentials

Be able to recognize the different protocols within TCP/IP and be able to define their purpose and function. The TCP/IP stack is made up of several protocols, which perform such functions as protocol transport, file access, file transfer, and mail transfer. These protocols include TCP, SMTP, IP, NNTP, HTTP, and FTP.
Be able to differentiate between the Internet, an internet, an intranet, and an extranet. When Internet is capitalized, it refers to the worldwide TCP/IP internetwork that we all know and love or hate, whereas internet is a more generic term referring to a network in which routers or other layer 3 devices are present. An intranet is an internetwork with well-defined administrative boundaries, while an extranet expands the intranet to include trusted outside networks. Be able to define the function of common TCP and UDP ports. You should know how to coordinate protocol name and function with port number. (Refer to Table 3.1 for specific examples.) Know how to identify IP addresses (IPv4, IPv6) and their default subnet masks. IPv4 =xxx.xxx.xxx.xxx, where xxx is a number from 0 to 255. The default subnet mask is 255.0.0.0
for a Class A address (IP range is 0.x.x.x to 127.x.x.x), 255.255.0.0 for a Class B (IP range is 128.x.x.x to 191.x.x.x), and 255.255.255.0 for a Class C (192.x.x.x to 223.x.x.x).
IPv6 = xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx, where x is a hexadecimal digit. IPv6 has no address classes and thus no default subnet mask. Know how to identify the purpose of subnetting and of default gateways. The purpose of subnetting is to divide a network into two or more segments, gaining more addressable segments from a single address space and reducing congestion. Default gateways are configured so that a host has an address to send an encapsulated packet to when it doesn’t know a specific
route to the destination address. Know how to identify the difference between public and private networks. Public networks
are networks that are open to the general public and, as such, use valid IP addresses that can be “seen” by the general public. The Internet is an example of a public network. Private networks,
on the other hand, use addresses that cannot be seen by the general public and are not available for public use or allowed onto the Internet in any way. Your company’s LAN is an example of
     a private network. These addresses must be translated to public addresses in order to allow the internal devices to communicate on the Internet. Identify the purpose, benefits, and characteristics of using a proxy service. A proxy server keeps a LAN somewhat separated from the Internet. Doing so increases security and filtering control and has the tendency to speed up Internet access through caching of recently used web pages. Be able to describe the main characteristics of VLANs. Virtual LANs (VLANs) are a feature of network switches that allow machines on different physical network segments to be organized into a virtual segment, or VLAN.