Cisco

Applications using UDP

Cisco

Application	Port Number(s)
DHCP	67, 68
DNS (name resolution)	53
TFTP	69
NTP	123
SNMP	161

Applications Using TCP

Cisco

Application	Port Number(s)
FTP	20, 21
Telnet	23
SMTP	25
DNS (zone transfers)	53
HTTP	80
POP3	110
NNTP	119
HTTPS	443

The Seven Layers of the OSI Model

Cisco

Layer Number	Layer Name
7	Application
6	Presentation
5	Session
4	Transport
3	Network
2	Data Link
1	Physical

All People Seem To Need Data Processing