cisco ccna study guide 2020

cisco ccna study guide 2020.192.168.0.0/16 network.Do not confuse the above address ranges with Class A, B, or C IP addresses, as the subnet masks are different.Each unit can choose one of the above private IP address ranges to assign an IP address to the intranet (either using traditional subnetting principles or VLSM principles). Readers will already know that when connecting their computer (for example, via Wi-Fi) to a home broadband router, they are generally assigned an IP address that begins with 192.168. This is because the IP address range provided by the broadband router for the local LAN is 192.168.0.0/16. Since two units can use the same IP address range, there may be two devices with the same IP address in the internal network of these two units. So, what can you do to make these two devices access each other? As mentioned before, the absolutePrivate IP address space should not be used on the Internet ± private IP addresses. So how can a host with a private IP address browse a Web server on the Internet? ziffl can use Network Address Translation (NAT) to solve this problem. NAT relies on the concepts of local IP addresses and global (or bottle-point public) IP addresses. A local IP address is an IP address assigned to a host on the unit's intranet, usually a private network IPFigure 1-51 Range of Private IP Addresses54 Chapter 1 Network Protocols and Network Device Basicsaddress. Other hosts on the unit's internal network will use this IP address to communicate with that host. A global IP address is an IP address that is outside the unit's internal network, for example, a public IP address.Note: Two hosts are not allowed to have the same IP address within the same subnet. If two hosts have the same IP address in the unit's internal network, you need to perform NAT in that internal network to allow those two hosts to access each other.Figure 1-52 shows how to allow two hosts with the same IP address and belonging to two different units to communicate with each other through NAT. Step 1. Host A sends a packet with a source IP address of 192.168.1.1 (local IP address)' and a destination IP address of 2.222 (global IP address of host B).Step 2. Upon receipt of the above packet, the Internet Gateway (GW1) in Unit A knows that it is Host A that needs to access the Internet ± the device. Therefore, GW1 will perform an address translation, replacing the value of the source IP address field in the packet header with the global IP address of host A (for example, replacing it with 1 ? 1.1). This step is indispensable, because the IP address 192.168.1.1 is only valid for the internal network of unit A, can not be routed on the Internet.