Domain 4 · 10% of the exam
IP Services
NAT, NTP, DHCP, DNS, SNMP, syslog, QoS, SSH, TFTP/FTP.
Domain 4 covers the “helper” services that make a network usable by real people. Routing and switching move packets, but it is these services that let a whole office share one public IP address (NAT), keep every device’s clock in agreement (NTP), hand out addresses automatically (DHCP), turn names into addresses (DNS), monitor devices (SNMP), record what happened (syslog), give voice calls priority over downloads (QoS), let you manage devices safely from your desk (SSH), and move files on and off routers (TFTP/FTP).
The domain is only 10% of the exam, but the topics are practical, the numbers are very testable (port numbers, severity levels, DSCP values), and the NAT and DHCP relay configurations show up in simulation-style questions. Every section below follows the same pattern: what the service does in plain English, the precise details, a configuration you can type on a real Cisco router, and the verification commands with sample output.
Objectives
- 4.1Configure and verify inside source NAT using static and pools
- 4.2Configure and verify NTP operating in a client and server mode
- 4.3Explain the role of DHCP and DNS within the network
- 4.4Explain the function of SNMP in network operations
- 4.5Describe the use of syslog features, including facilities and severity levels
- 4.6Configure and verify DHCP client and relay
- 4.7Explain the forwarding per-hop behavior (PHB) for QoS
- 4.8Configure network devices for remote access using SSH
- 4.9Describe the capabilities and functions of TFTP/FTP in the network