cisco ccna 200-301 volume 2

cisco ccna 200-301 volume 2.Router(config)# access-list 100 permit ip any anyThis configuration only prohibits traffic from 192.168.5.1 to 192.168.1.1 from passing through. The next question is, where should this ACL be placed? Again, this ACL should be placed as close to the source device as possible. This means that it should be placed on Router C, but Router C has two interfaces. However, placing the ACL as close to the source device as possible means that it should be placed in the inbound direction of interface E1. If it is placed on interface E0, the source device will be able to bypass the filter if router C has another interface available to it for travel to the target device. If the ACL is placed on interface E1 of router C, 192.168.5.1 will be able to access all other devices except 192.168.1.1; and no other traffic in the network will be filtered out.The filtering for this example can be more specific. For example, if you only want to block 192.168.5.1 from accessing 192.168.1.1 via Telnet, but allow it to access 192.168.1.1 in other ways, you should specify the IP protocol (tcp) and the destination port name or port number (telnet or 23).In practice, standard ACLs are rarely used to filter traffic. In very old versions of IOS, the performance difference between using standard ACLs and extended ACLs is significant - processing standard ACLs is much faster. However, on the latest router platforms using newer IOS versions, this difference does not exist. With this in mind, only Extended ACLs should be used to filter traffic going to or through the router.Exam Requirements ACL OverviewIt is likely that you will encounter some exam questions related to ACLs and ACL troubleshooting on the exam; in Cisco's view, this topic is more important than others because ACLs are a common tool on IOS devices. Don't forget that in addition to filtering traffic passing through the IOS device, ACLs have other uses, such as restricting access to the device via VTY. When filtering traffic, inbound ACLs are processed first, and then traffic is forwarded to the destination interface. It is important to know the similarities and differences between standard and extended IP ACLs and what information they can each filter based on. Be sure to know how ACLs are handled and how to arrange statements in ACLs.Be sure to know the syntax for creating IP standard and extended ACLs, including the numbering that is available to the prospective users. You need to be familiar with wildcard masks and how to use them to match address ranges. Keep in mind the following trick: Subtract the subnet mask from the local broadcast address to get the corresponding wildcard mask Q You may encounter troubleshooting problems with incorrectly configured wildcard masks, so it is important to be able to find the correct wildcard mask for the range of addresses to be matched. Do not forget that ACLs are activated in the inbound and/or outbound direction of the interface. On the exam, you may be asked to create an extended ACL with two or three statements, then activate and test it; recommend the ACL configuration that should be used; and even troubleshoot the ACL configuration. ACL configuration is one of the important topics on the exam.ACL TypesDon't forget that if a wildcard mask is omitted from a standard ACL, it will end in 0.0.0.0 (matching only specific hosts)Chapter 21 Access Control Lists 575