Network security practice: What are the two main types of access control lists (ACLs) used on routers and firewalls?

Introduction / Context:
Access control lists (ACLs) are rule sets that permit or deny traffic based on criteria such as source, destination, and protocol. On many network platforms, especially Cisco IOS, two broad categories are emphasized for IP traffic filtering.

Given Data / Assumptions:

• The numbered items are: 1 Standard, 2 IEEE, 3 Extended, 4 Specialized.
• We are referring to commonly taught ACL categories for IP filtering.
• Standard and extended ACLs are the canonical types in core certification curricula.

Concept / Approach:
Standard ACLs filter based on source IP only, typically applied as inbound or outbound on interfaces. Extended ACLs provide granular matching, including source, destination, protocol (TCP, UDP, ICMP), and ports. Other labels such as IEEE or specialized are not the established base types for IP ACLs in Cisco nomenclature.

Step-by-Step Solution:

Verification / Alternative check:
Configuration guides show ip access-list standard and ip access-list extended modes, confirming the two major types.

Why Other Options Are Wrong:

• Pairs involving IEEE or Specialized do not reflect the standard Cisco categories.
• Standard and Extended are the widely recognized main types for IP ACLs.

Common Pitfalls:
Placing standard ACLs too close to the destination rather than the source; forgetting that extended ACLs should be placed close to the source for efficiency and specificity.

Final Answer:
1 and 3