tailieunhanh - CompTIA Network+ Certification Study Guide part 37

CompTIA’s Network+ certification Study Guide part 37 is a globally-recognized, vendor neutral exam that has helped over 235,000 IT professionals reach further and higher in their careers. The 2009 Network+ exam (N10-004) is a major update with more focus on security and wireless aspects of networking. Our new study guide has been updated accordingly with focus on network, systems, and WAN security and complete coverage of today’s wireless networking standards. | 346 CHAPTER 7 TCP IP and Routing identifiers of a number of private hosts to be multiplexed into the transport identifiers of a single global IP address. PAT allows numerous hosts from the internal network to share a single external network IP address. The advantage of this type of translation is that only one global IP address is needed whereas with NAT each internal host must translate to a unique external IP address. PAT can be particularly useful for locations or users connected via cable modem digital subscriber line DSL or other similar arrangement wherein they are provided a single global public IP address. In such scenarios all inside addresses are translated to this single address. Exam Warning NAT hides the local internal IP addresses from external Internet users which provides a layer of security to your network. SUMMARY OF EXAM OBJECTIVES Understanding TCP IP from the ground up is required to effectively manage a network whether LAN or WAN. TCP IP is a suite of protocols originally developed by the Department of Defense in a project called the Advanced Research Projects Agency DARPA . The first WAN implemented using these protocols was called the Advanced Research Projects Agency Network ARPANET . It was during this time that TCP IP was designed and developed as a standardized way for computers to communicate across a network. From the DARPA experiment came the understanding that networking would become increasingly common - and increasingly complex. The OSI model was developed based on the DARPA model and approved by OSI subcommittee of the International Organization for Standardization ISO . The OSI model defined seven layers for standard reliable network communications physical data link network transport session presentation and application. The acronym commonly used to remember this is in reverse order All People Seem To Need Data Processing. The OSI model was covered in depth in Chapter 5. It will however continue to be used through the rest of .