This Quiz On CCNA 4, Chapter 4 Exam

The wildcard mask that is associated with the network 192.168.12.0/24 is 0.0.0.255. In a wildcard mask, the bits that are set to 0 indicate the network portion, and the bits that are set to 1 indicate the host portion. Since the network address 192.168.12.0 has a subnet mask of /24, it means that the first 24 bits are used for the network portion and the remaining 8 bits are used for the host portion. In the wildcard mask, the bits that correspond to the host portion are set to 1, which is represented by 0.0.0.255.

The line 3 of the access list is "permit tcp any host 10.0.70.5 eq www", which allows TCP traffic from any source IP address to the destination IP address 10.0.70.5 on port 80 (HTTP). Since the request for information from a secure web page is sent from host 10.0.55.23 to the 10.0.70.5 server, this line will match the traffic and the router will forward the packet onward.

The given wildcard mask of 0.0.7.255 indicates that the first three octets of the IP address (10.120.160) are fixed, while the last octet can range from 0 to 255. Therefore, the range of IP addresses affected will be from 10.120.160.0 to 10.120.167.255.

The reason for the connection failure is that the IT group network is included in the deny statement of the ACL. This means that the ACL is explicitly blocking any connections from the IT group workstations in the network 192.168.22.0/28. As a result, when the ACL is applied to the interface Fa0/0, Telnet connections from the workstation with IP 192.168.22.5 are denied.

When applying an ACL to a router interface, outbound traffic refers to the traffic that is leaving the router and going towards the destination host. This means that the router is filtering the traffic that is being transmitted from the router to the destination host. The ACL is applied to the interface to control and restrict the outbound traffic based on the defined rules and criteria.

IPv6 ACLs have an implicit permit of neighbor discovery packets, which means that these packets are allowed by default without explicitly configuring a rule for them. This is a unique feature of IPv6 ACLs compared to IPv4 ACLs, where neighbor discovery packets would require a specific rule to permit them.

The two ACE commands that will block traffic destined for a web server listening on default ports are "access-list 110 deny tcp any any eq https" and "access-list 110 deny tcp any any gt 75". The first command denies any TCP traffic with a destination port of 443, which is the default port for HTTPS. The second command denies any TCP traffic with a destination port greater than 75, which would include all ports commonly used for web traffic. By using these two commands, any traffic attempting to access the web server on default ports will be blocked.

The LIMITED_ACCESS IPv6 access list on R1 is applied inbound on the S0/0/0 interface. This means that any packets coming from the ISP and destined to PC1 will be checked against this access list. The access list is configured to drop ICMPv6 packets that are destined to PC1, so any ICMPv6 packets with PC1 as the destination will be dropped by the ACL on R1.

Access Control Lists (ACLs) are used to control network traffic and provide security by allowing or denying access to network resources. They can restrict access to specific applications and ports, thus providing a basic level of security for network access. Additionally, ACLs can control which areas a host can access on a network, allowing administrators to define and enforce network segmentation and access policies. ACLs do not assist routers in determining the best path to a destination, nor do they permit or deny traffic based on MAC addresses originating from the router.

When creating an extended access control list entry, three values or sets of values that are included are: access list number between 100 and 199, destination address and wildcard mask, and source address and wildcard mask. These values are necessary to define the specific traffic that the access control list will permit or deny. The access list number determines the order in which the access control list entries are processed. The destination address and wildcard mask specify the destination IP address or range of addresses that the access control list will match. Similarly, the source address and wildcard mask specify the source IP address or range of addresses that the access control list will match.

A network administrator could use the packet filters "ICMP message type" and "destination UDP port number" on an IPv4 extended ACL. The "ICMP message type" filter allows the administrator to control the types of ICMP messages that are allowed or denied. The "destination UDP port number" filter allows the administrator to control which UDP ports are allowed or denied as destinations for incoming packets. These filters provide control over specific types of network traffic based on their characteristics, allowing for more granular security and network management.

The correct answer is "ipv6 traffic-filter ENG_ACL in". This command is used to activate an IPv6 ACL named ENG_ACL on an interface. The "in" keyword indicates that the ACL should be applied to incoming traffic, filtering it before it is processed by the routing table.

The most efficient wildcard mask to use when specifying all of these networks in a single ACL permit entry is 0.0.1.255. This wildcard mask will match all the given networks (192.168.1.0/25, 192.168.0.0/25, 192.168.0.128/25, 192.168.1.128/26, and 192.168.1.192/26) because it allows for any value in the last octet while keeping the first three octets constant. This ensures that only the specified networks are permitted and no other traffic is allowed, maintaining security.

The wildcard mask 0.0.0.15 means that the last four bits of a supplied IP address will be ignored. This means that any IP address that matches the first 28 bits of the supplied IP address will be allowed or denied access, depending on the configuration. Therefore, the first 28 bits of a supplied IP address will be matched by the access control list.

Extended ACLs evaluate the source and destination addresses, allowing for more granular control over network traffic. Port numbers can also be used in extended ACLs to further define the type of traffic that is allowed or denied.

The correct answer is "permit tcp any host 2001:DB8:10:10::100 eq 25". This command entry allows any host to establish a TCP connection with the SMTP server on network 2001:DB8:10:10::/64 by permitting TCP traffic from any source IP address to the destination IP address 2001:DB8:10:10::100 on port 25, which is the port commonly used for SMTP (Simple Mail Transfer Protocol).

The first ACE "access-list 100 deny ip host 10.1.1.1 192.168.0.0 0.0.255.255" denies IP traffic from the source host 10.1.1.1 to the destination network 192.168.0.0/16. The second ACE "access-list 100 deny ip 10.1.1.1 0.0.0.0 192.168.0.0 0.0.255.255" also denies IP traffic from the source host 10.1.1.1 to the destination network 192.168.0.0/16, but it uses a wildcard mask for the source IP address. Both ACEs achieve the same result of denying traffic from the specified source host to the specified destination network.

The given set of access control entries allows all users on the 192.168.10.0/24 network to access the web server located at 172.17.80.1 by permitting TCP traffic from the network to the server on port 80. It also denies any TCP traffic from the network to any destination on port 23, effectively blocking Telnet access.

The router will forward the packet with destination IP address 192.168.83.189 and protocol FTP because the access list permits any IP traffic to that specific IP address range. The deny statement in the access list only applies to TCP traffic with a source IP address within the LAN segment and a destination port of 23. Since the destination IP address 192.168.83.189 does not match the deny statement criteria, the packet will be forwarded.

The correct ACL to filter the traffic is access-list 105 permit tcp host 10.0.70.23 host 10.0.54.5 eq 20, access-list 105 permit tcp host 10.0.70.23 host 10.0.54.5 eq 21, access-list 105 permit tcp 10.0.0.0 0.255.255.255 host 10.0.54.5 eq www, access-list 105 deny ip any host 10.0.54.5, and access-list 105 permit ip any any. The ACL allows TCP traffic from the host 10.0.70.23 to the FTP server on ports 20 and 21, and allows TCP traffic from any internal network to the FTP server on port 80. It then denies any IP traffic from any source to the FTP server and allows all other IP traffic. The ACL is applied out on the R1 Gi0/0 interface and the R1 S0/0/0 interface.

The first command "access-list 101 permit ip host 192.168.1.1 host 192.168.2.1" creates an access control list (ACL) rule that permits IP traffic from host 192.168.1.1 to host 192.168.2.1.

The second command "interface fastethernet 0/0" enters the configuration mode for the FastEthernet interface 0/0.

The third command "ip access-group 101 in" applies the ACL with the number 101 to inbound traffic on the interface.

These three commands together allow only the specified host to access the specified server by filtering traffic at the interface level.

The router will drop the packets with the destination IP address of 202.16.83.131 and protocol HTTP, as well as the packets with the destination IP address of 192.168.83.157 and protocol Telnet. This is because the first line of the access list denies TCP traffic from the IP address range 192.168.83.64/26 (which includes both of these destination IP addresses) to any destination with port 23 (Telnet). The second line of the access list permits all other IP traffic within the same IP address range.