CCNA 2 Chapter 7 V6.0 Answers

1. Consider the following output for an ACL that has been applied to a router via the access-class in command. What can a network administrator determine from the output that is shown?

R1#

Standard IP access list 2

10 permit 192.168.10.0, wildcard bits 0.0.0.255 (2 matches)

20 deny any (1 match)

Traffic from two devices was allowed to enter one router port and be routed outbound to a different router port.

Two devices were able to use SSH or Telnet to gain access to the router.

Two devices connected to the router have IP addresses of 192.168.10.x.

Traffic from one device was not allowed to come into one router port and be routed outbound a different router port.

 

2. On which router should the show access-lists command be executed?

On any router through which the packet referenced in the ACL travels

on the router that routes the packet referenced in the ACL to the final destination network

on the router that routes the packet referenced in the ACL from the source network

on the router that has the ACL configured

 

3. Refer to the following output. What is the significance of the 4 match(es) statement?

R1#

10 permit 192.168.1.56 0.0.0.7

20 permit 192.168.1.64 0.0.0.63 (4 match(es))

30 deny any (8 match(es))

Four packets have been allowed through the router to reach the destination network of 192.168.1.64/26.

Four packets have been denied that are destined for the 192.168.1.64 network.

Four packets have been allowed through the router from PCs in the network of 192.168.1.64.

Four packets have been denied that have been sourced from any IP address.

 

4. Refer to the exhibit.

An ACL was configured on R1 with the intention of denying traffic from subnet 172.16.4.0/24 into subnet 172.16.3.0/24. All other traffic into subnet 172.16.3.0/24 should be permitted. This standard ACL was then applied outbound on interface Fa0/0. Which conclusion can be drawn from this configuration?

Which conclusion can be drawn from this configuration?

Only traffic from the 172.16.4.0/24 subnet is blocked, and all other traffic is allowed.

The ACL should be applied outbound on all interfaces of R1.

All traffic will be blocked, not just traffic from the 172.16.4.0/24 subnet.

The ACL should be applied to the FastEthernet 0/0 interface of R1 inbound to accomplish the requirements.

An extended ACL must be used in this situation.

 

5. If a router has two interfaces and is routing both IPv4 and IPv6 traffic, how many ACLs could be created and applied to it?

4

8

12

16

6

 

6. Which feature will require the use of a named standard ACL rather than a numbered standard ACL?

the ability to specify source and destination addresses to use when identifying traffic

the ability to filter traffic based on a specific protocol

the ability to add additional ACEs in the middle of the ACL without deleting and re-creating the list

the ability to filter traffic based on an entire protocol suite and destination

 

7. Which type of ACL statements are commonly reordered by the Cisco IOS as the first ACEs?

permit any

host

range

lowest sequence number

 

8. A network administrator is configuring an ACL to restrict access to certain servers in the data center. The intent is to apply the ACL to the interface connected to the data center LAN. What happens if the ACL is incorrectly applied to an interface in the inbound direction instead of the outbound direction?

The ACL will analyze traffic after it is routed to the outbound interface.

All traffic is denied.

The ACL does not perform as designed.

All traffic is permitted.

 

9. What single access list statement matches all of the following networks?

192.168.16.0

192.168.17.0

192.168.18.0

192.168.19.0

access-list 10 permit 192.168.16.0 0.0.15.255

access-list 10 permit 192.168.16.0 0.0.3.255

access-list 10 permit 192.168.0.0 0.0.15.255

access-list 10 permit 192.168.16.0 0.0.0.255

 

10. What is the quickest way to remove a single ACE from a named ACL?

Create a new ACL with a different number and apply the new ACL to the router interface.

Use the no access-list command to remove the entire ACL, then recreate it without the ACE.

Use the no keyword and the sequence number of the ACE to be removed.

Copy the ACL into a text editor, remove the ACE, then copy the ACL back into the router.

 

11. A network administrator needs to configure a standard ACL so that only the workstation of the administrator with the IP address 192.168.15.23 can access the virtual terminal of the main router. Which two configuration commands can achieve the task? (Choose two.)

Router1(config)# access-list 10 permit 192.168.15.23 0.0.0.0

Router1(config)# access-list 10 permit 192.168.15.23 0.0.0.255

Router1(config)# access-list 10 permit 192.168.15.23 255.255.255.255

Router1(config)# access-list 10 permit 192.168.15.23 255.255.255.0

Router1(config)# access-list 10 permit host 192.168.15.23

 

12. What is the effect of configuring an ACL with only ACEs that deny traffic?

The ACL will block all traffic.

The ACL must be applied outbound only.

The ACL will permit any traffic that is not specifically denied.

The ACL must be applied inbound only.

 

13. Refer to the exhibit.

If the network administrator created a standard ACL that allows only devices that connect to the R2 G0/0 network access to the devices on the R1 G0/1 interface, how should the ACL be applied?

how should the ACL be applied?

inbound on the R1 G0/1 interface

outbound on the R1 G0/1 interface

outbound on the R2 S0/0/1 interface

inbound on the R2 G0/0 interface

 

14. Refer to the exhibit. Which command would be used in a standard ACL to allow only devices on the network attached to R2 G0/0 interface to access the networks attached to R1?

Which command would be used in a standard ACL to allow only devices on the network attached to R2 G00 interface to access the networks attached to R1?

access-list 1 permit 192.168.10.96 0.0.0.31

access-list 1 permit 192.168.10.0 0.0.0.255

access-list 1 permit 192.168.10.128 0.0.0.63

access-list 1 permit 192.168.10.0 0.0.0.63

 

15. In which configuration would an outbound ACL placement be preferred over an inbound ACL placement?

When an outbound ACL is closer to the source of the traffic flow

when an interface is filtered by an outbound ACL and the network attached to the interface is the source network being filtered within the ACL

when a router has more than one ACL

when the ACL is applied to an outbound interface to filter packets coming from multiple inbound interfaces before the packets exit the interface

 

16. Which statement describes a difference between the operation of inbound and outbound ACLs?

Inbound ACLs can be used in both routers and switches but outbound ACLs can be used only on routers.

Inbound ACLs are processed before the packets are routed while outbound ACLs are processed after the routing is completed.

On a network interface, more than one inbound ACL can be configured but only one outbound ACL can be configured.

In contrast to outbound ALCs, inbound ACLs can be used to filter packets with multiple criteria.

 

17. Which address is required in the command syntax of a standard ACL?

destination IP address

source IP address

source MAC address

destination MAC address

 

18. An administrator has configured an access list on R1 to allow SSH administrative access from host 172.16.1.100. Which command correctly applies the ACL?

R1(config-if)# ip access-group 1 out

R1(config-line)# access-class 1 out

R1(config-if)# ip access-group 1 in

R1(config-line)# access-class 1 in

 

19. Which three statements are generally considered to be best practices in the placement of ACLs? (Choose three.)

Filter unwanted traffic before it travels onto a low-bandwidth link.

Place extended ACLs close to the source IP address of the traffic.

For every inbound ACL placed on an interface, there should be a matching outbound ACL.

Place standard ACLs close to the destination IP address of the traffic.

Place extended ACLs close to the destination IP address of the traffic.

Place standard ACLs close to the source IP address of the traffic.

 

20. Refer to the exhibit. A router has an existing ACL that permits all traffic from the 172.16.0.0 network. The administrator attempts to add a new ACE to the ACL that denies packets from host 172.16.0.1 and receives the error message that is shown in the exhibit. What action can the administrator take to block packets from host 172.16.0.1 while still permitting all other traffic from the 172.16.0.0 network?

A router has an existing ACL that permits all traffic from the 172.16.0.0 network

Manually add the new deny ACE with a sequence number of 15.

Add a deny any any ACE to access-list 1.

Manually add the new deny ACE with a sequence number of 5.

Create a second access list denying the host and apply it to the same interface.

 

21. Which type of router connection can be secured by the access-class command?

Ethernet

vty

console

serial

 

22. When would a network administrator use the clear access-list counters command?

when buffer memory is low

when an ACE is deleted from an ACL

when troubleshooting an ACL and needing to know how many packets matched

when obtaining a baseline

 

23. Match each statement with the example subnet and wildcard that it describes. (Not all options are used.)

Match each statement with the example subnet and wildcard that it describes

Place the options in the following order:

192.168.15.65 255.255.255.240 ==> the first valid host address in a subnet

192.168.15.144 0.0.0.15 ==> subnetwork address of a subnet with 14 valid host addreses

host 192.168.15.12 ==> all IP address bits must match exactly

192.168.5.0 0.0.3.255 ==> hosts in a subnet with SM 255.255.252.0

192.168.3.64 0.0.0.7 ==> address with a subnet 255.255.255.248

 

24. Refer to the exhibit. What will happen to the access list 10 ACEs if the router is rebooted before any other commands are implemented?

What will happen to the access list 10 ACEs if the router is rebooted before any other commands are implemented?

The ACEs of access list 10 will be deleted.

The ACEs of access list 10 will be renumbered.

The ACEs of access list 10 will not be affected.

The ACEs of access list 10 wildcard masks will be converted to subnet masks.

 

25. Which three statements describe ACL processing of packets? (Choose three.)

An implicit deny any rejects any packet that does not match any ACE.

Each packet is compared to the conditions of every ACE in the ACL before a forwarding decision is made.

Each statement is checked only until a match is detected or until the end of the ACE list.

A packet can either be rejected or forwarded as directed by the ACE that is matched.

A packet that does not match the conditions of any ACE will be forwarded by default.

A packet that has been denied by one ACE can be permitted by a subsequent ACE.

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