Standard IPv4 ACLs Configuration Quiz

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Questions and Answers

What command is used to create a numbered standard IPv4 ACL?

create access-list

access-list (correct)

configure acl

ip access-list standard

Which of the following is NOT a valid access-list number for a numbered standard ACL?

1300

1500 (correct)

What is the function of the 'deny' command in a standard IPv4 ACL?

Allow all traffic

Block specific traffic (correct)

Permit traffic by default

Log denied traffic

What parameter is optional and provides documentation in a numbered standard ACL?

remark text Signup and view all the answers

What is true regarding the naming of a standard named ACL?

Names must be unique. Signup and view all the answers

What is the purpose of the 'log' option in a standard IPv4 ACL?

To generate an informational message when an ACE is matched Signup and view all the answers

What command would you use to remove a numbered standard ACL?

no access-list access-list-number Signup and view all the answers

Which wildcard mask is applied to the source in a numbered standard ACL?

32-bit wildcard mask Signup and view all the answers

What command is used to bind a standard IPv4 ACL to an interface?

ip access-group Signup and view all the answers

Which command is used to remove an ACL from an interface?

no ip access-group Signup and view all the answers

In an example numbered standard ACL, which IP address is allowed traffic?

192.168.10.10 Signup and view all the answers

What should you use to verify that an ACL is applied to the interface?

show ip interface Signup and view all the answers

What is the primary function of ACL 120 as described?

To permit returning web traffic to the inside hosts Signup and view all the answers

What does the notation 192.168.20.0/24 represent in the ACL example?

A subnet with 256 addresses Signup and view all the answers

What is the advantage of using named standard ACLs over numbered ones?

Easier to remember and manage Signup and view all the answers

What flag must be set for a packet to match the existing TCP connection according to the information provided?

ACK or RST flag Signup and view all the answers

Which command is used to create a named extended ACL?

ip access-list extended Signup and view all the answers

Which interface was used in the ACL example for permitting traffic?

serial 0/1/0 Signup and view all the answers

What does the named extended ACL called BROWSING permit?

Only returning web traffic to inside hosts Signup and view all the answers

What type of ACL is primarily concerned with layer 3 IP traffic?

Standard ACL Signup and view all the answers

Which command would you issue to view the current configuration of an ACL?

show running-config Signup and view all the answers

What is the effect of applying Extended ACLs on the R1 G0/0/0 interface?

It denies all traffic by default unless explicitly permitted Signup and view all the answers

What structure does a standard IPv4 ACL follow?

Permit or deny traffic based only on IP address Signup and view all the answers

What is the primary purpose of a named ACL in IPv4?

To manage and apply access control rules using sequence numbers Signup and view all the answers

What command is used to display statistics for each ACE in an ACL?

show access-lists Signup and view all the answers

Which statement about the deny any command is true?

It must be manually configured to track denied packets. Signup and view all the answers

How can an administrator reset the ACL statistics?

execute the clear access-list counters command Signup and view all the answers

What does the implied deny any statement do in an access control list?

Blocks all traffic unless otherwise specified. Signup and view all the answers

In the provided example, which IP address is denied access?

192.168.10.11 Signup and view all the answers

What is one of the objectives of the Packet Tracer activity mentioned?

Configure and verify standard numbered and named ACLs Signup and view all the answers

When an ACE is matched, which of the following is true about its statistics?

Both deny and permit ACEs show statistics. Signup and view all the answers

What is a characteristic of sequence numbers in named ACLs?

They help in the ordering of ACEs. Signup and view all the answers

What will happen if an ACE specifically permits an IP address?

Only that IP address will be allowed connectivity. Signup and view all the answers

What is the port number used for HTTP traffic in the configuration of extended ACLs?

80 Signup and view all the answers

What is the main purpose of the extended ACL 100 as stated in the configuration example?

To filter HTTP traffic Signup and view all the answers

Where are extended ACLs commonly applied according to the configuration examples?

Close to the source Signup and view all the answers

What does the established keyword in a TCP extended ACL allow?

Return traffic from inside to outside Signup and view all the answers

When is it necessary to configure a port number instead of a protocol name in ACLs?

When the protocol name is unknown Signup and view all the answers

What is the effect of applying ACL 110 inbound on the R1 G0/0/0 interface?

Permits HTTP and HTTPS traffic from a specific network Signup and view all the answers

Which of the following protocols has a specific port number listed in the examples?

SSH Signup and view all the answers

What traffic is denied by the TCP established extended ACL?

TCP traffic from outside hosts to inside hosts Signup and view all the answers

Which ACE approach achieves the same filtering result for HTTP traffic?

Using the port name www Signup and view all the answers

Which type of ACL is particularly designed to filter based on port numbers?

Extended ACL Signup and view all the answers

Study Notes

Standard IPv4 ACLs - Configuration and Syntax

Numbered standard ACLs range from 1 to 99 or 1300 to 1999 using the access-list command.
Key commands:
- deny: Blocks access if matched.
- permit: Allows access if matched.
- remark: Adds documentation (optional).
- source: Specifies the address filtering.
- source-wildcard: Optional 32-bit wildcard mask for the source.
- log: Generates messages upon ACE match (optional).
To delete a numbered ACL, use no access-list access-list-number.

Named Standard IPv4 ACLs

Named ACLs are created with ip access-list standard, requiring unique, case-sensitive names.
Naming ACLs enhances clarity within configuration outputs.

Applying Standard IPv4 ACLs

After configuration, link ACLs to an interface using ip access-group.
Remove an ACL with no ip access-group in interface configuration.

Examples of Standard IPv4 ACLs

A numbered ACL example permits traffic from host 192.168.10.10 and the 192.168.20.0/24 network out interface serial 0/1/0 on router R1.
Use show running-config to view ACLs and show ip interface to verify applied ACLs.

Modifying IPv4 ACLs

Named ACLs can utilize sequence numbers to manage ACEs; example includes denying host 192.168.10.11.
Use show access-lists for statistics on matched statements from ACLs; implicit deny statistics require a manual deny command for visibility.

Extended IPv4 ACLs - Configuration

Extended ACLs allow filtering based on port numbers/names; example filters HTTP traffic using both port name and number 80.
Apply extended ACLs close to the source for more control over traffic flow.

TCP Established Extended ACLs

Use the TCP established keyword to permit returning traffic from established connections, blocking unsolicited inbound traffic.
Example configuration allows returning web traffic to inside hosts, applied outbound on the R1 G0/0/0 interface.

Named Extended IPv4 ACLs

Named extended ACLs created with ip access-list extended facilitate understanding of ACL functions.
Example shows creating NO-FTP-ACCESS for clarity in ACL management.

Applying Named Extended IPv4 ACLs

Two named extended ACLs demonstrate application:
- SURFING: Permits inside HTTP and HTTPS traffic to exit to the internet.
- BROWSING: Allows only returning web traffic to inside hosts while implicitly denying other outbound traffic.

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Description

Test your knowledge on Standard IPv4 Access Control Lists (ACLs) configuration and syntax. This quiz covers key commands, the differences between numbered and named ACLs, and their application on network interfaces. Perfect for networking students and professionals looking to sharpen their skills.