Cisco CCNA Access Control Lists (ACLs) 3

Question 1

What is the effect of the implicit deny at the end of every ACL?

Accepted Answer

It drops all traffic that does not match any ACL entry

Answer

Every ACL ends with an implicit 'deny any' that silently drops any traffic not matched by a previous entry.

Question 2

Which ACL type can filter traffic based on both source AND destination IP address?

Accepted Answer

Extended ACL

Answer

Extended ACLs can match on source IP, destination IP, protocol, and port numbers.

Question 3

Which command verifies which ACLs are applied to a specific interface and their direction?

Accepted Answer

show ip interface

Answer

'show ip interface' displays the inbound and outbound ACLs applied to each interface.

Question 4

A network administrator needs to block only Telnet traffic from host 10.1.1.1 to any destination. Which ACL entry achieves this?

Accepted Answer

access-list 100 deny tcp host 10.1.1.1 any eq 23

Answer

Telnet uses TCP port 23; the source is the host and destination is 'any'.

Question 5

Which wildcard mask matches the entire subnet 172.16.0.0/16?

Accepted Answer

0.0.255.255

Answer

A /16 prefix means 16 bits are fixed, so the wildcard mask is 0.0.255.255, allowing the last 16 bits to vary.

Cisco CCNA Practice Test