This chapter covers
- The importance of date and time on network devices
- Manually setting the date and time on Cisco routers and switches
- How NTP enables devices to synchronize their clocks over a network
- Configuring and securing NTP on Cisco routers and switches
When you think of the most important functions of a router or switch, keeping accurate date and time information is probably not among the first things that come to mind. However, timekeeping that is accurate and consistent across all devices is critical for a variety of functions and services in a network, from security protocols to logging. So how can we achieve accurate timekeeping on our network devices?
The answer is Network Time Protocol (NTP), the topic of this chapter. Using NTP, devices across a network can synchronize their clocks to a common time source. NTP isn’t limited to just network infrastructure devices like routers and switches; it’s used by all kinds of network-connected devices, including smartphones, PCs, and servers. In this chapter, we’ll cover CCNA exam topic 4.2: Configure and verify NTP operating in a client and server mode.
2.1 Date and time on network devices
Accurate date and time information on network devices is more important than you might expect. In this section, we’ll look at a few reasons why that is. We’ll also cover how to manually configure the date and time on Cisco IOS devices before covering NTP itself in section 2.2.