tailieunhanh - CompTIA Network+ Certification Study Guide part 35

CompTIA’s Network+ certification Study Guide part 35 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. | 326 CHAPTER 7 TCP IP and Routing In a more technical definition DHCP is a communications protocol that allows you to manage IP addressing usage centrally and to automate the assignment of logical addresses in an organization s network. Remember each host on the network needs a unique IP address to be able to communicate. When an organization sets up its computer users with a connection to the Internet an IP address must be assigned to each machine. Without DHCP the IP address must be entered manually at each computer and if computers move to another location in another part of the network a new IP address must be entered. DHCP lets a network administrator supervise and distribute IP addresses from a central point and automatically sends a new IP address when a computer is plugged into a different place in the network. DHCP uses the concept of a lease or amount of time that a given IP address will be valid for a computer. The lease time can vary depending on how long a user is likely to require the Internet connection at a particular location. It s especially useful in education and other environments where users change frequently. Using very short leases DHCP can dynamically reconfigure networks in which there are more computers than there are available IP addresses. DHCP supports static addresses for computers containing Web servers that need a permanent IP address you can make reservations for such addresses. DHCP is an extension of an earlier network IP management protocol Bootstrap Protocol BOOTP . DHCP is a more advanced protocol but both configuration management protocols are commonly used and DHCP can handle BOOTP client requests. Some organizations use both protocols but understanding how and when to use them in the same organization is important. Some operating systems including Windows NT 2000 come with DHCP servers. A DHCP or BOOTP client is a program that is located in and perhaps downloaded to each computer so that it can be configured. Note DHCP and .