An inbound access list has been configured on a serial interface to deny packet entry for TCP and
UDP ports 21, 23 and 25. What types of packets will be permitted by this ACL? (Choose three.)
A.
HTTP
B.
FTP
C.
POP3
D.
Telnet
E.
SMTP
F.
DNS
Explanation:
The most often used port numbers of TCP/UDP are as follows:
The port numbers of TCP:
20 FTP data
21 FTP control
23 Telnet
25 SMTP
53 DNS
80 WWW
110 POP3
The port numbers of UDP
53DNS
69 TFTP
161 SNMP
NotE. DNS uses TCP to perform Zone Transfers and UDP to query name .
The ACL created on the router denied the traffic from the ports 21, 23, 25, thus allowing these
three types of traffic such as DNS, POP3, HTTP to cross .