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TechKnowSurge Catalog Videos DEMO: Setting the Clock
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DEMO: Setting the Clock

Accurate time synchronization across network devices is essential for log correlation, security auditing, and incident investigation. This content covers manual clock configuration and NTP server setup on network equipment.

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About this video

Accurate time synchronization is a critical but often overlooked element of network administration and security operations. On small networks the impact of mismatched clocks may be minimal, but as infrastructure grows, the consequences of time drift compound quickly. Security protocols depend on synchronized time to function correctly, and log aggregation — the process of pulling event data from multiple devices to monitor or troubleshoot the network — becomes unreliable when timestamps are inconsistent across systems. The real-world stakes become clear during a security incident. If an attacker compromises one device and moves laterally through the network, escalating privileges along the way, investigators must reconstruct that sequence of events from log data. When device clocks disagree, that reconstruction becomes difficult or impossible. Precise, synchronized timestamps are what make forensic analysis actionable. Two approaches address this problem. The first is manual configuration using the clock set command on individual devices, specifying hours, minutes, seconds, date, month, and year. While straightforward, manual configuration is prone to drift over time and does not scale across a large environment. The more robust solution is Network Time Protocol, or NTP, which allows all devices on the network to reference a single authoritative time source — either an internal server that syncs outward to the internet, or an external source directly. With NTP in place, any drift is automatically corrected, and every device on the network maintains second-level accuracy without ongoing manual intervention.

What you'll learn

What's covered

Network Time Configuration

Aligned to

Cisco CCNA
4.5 Describe the use of syslog features, including facilities and severity levels
4.2 Configure and verify NTP operating in client and server mode
Cisco CCST Cybersecurity
3.5 Interpret system logs
Cisco CyberOps Associate
3.5 Interpret OS, SIEM, SOAR platform, application, or command line logs to identify an event

Key terms

Network Time Protocol
NTP
A protocol that synchronizes the clocks of networked devices to a common reference time source using a hierarchy of time servers called strata, operating over UDP port 123. Accurate time synchronization is critical for security logging, authentication tickets, and correlating events across devices.
Log Management
The process of collecting, storing, analyzing, and monitoring log data generated by systems and applications.
Time Synchronization
The process of coordinating clocks across network devices to ensure consistent and accurate timestamps for logging and security analysis.

Topics

Ntp Time Synchronization Cisco Ios Network Administration Log Correlation Cli Configuration Networking

Transcript

Why time matters on your devices

This is actually a pretty simplistic topic, and it's really easy to set it up on your devices, but it could have pretty big ramifications if you're dealing with larger networks, and that is time. It's important to set your time correctly.

When you're dealing with small networks, it may not be a big deal for your equipment to all be on the same time, but as your network grows it's going to become more important. There is some security that requires time to be accurate in order for the security measures to work. But really, what I'm talking about more right here with these devices is when you are aggregating logs, or you're trying to find out information about your network, or you're pulling together, you're trying to research different issues that have happened on your network. Those timestamps become more important.

Let me give you a more specific example. Let's say somebody hacks your network. If they've hacked into your network, they might have hacked a certain piece of equipment and then started leveraging other pieces of equipment and escalating their privileges. As you're going and exploring this, if you want to track what devices they compromised and when they compromised them, and find that trail out, you're going to need to know accurate timestamps. If your times are all off on your equipment, that's going to be very difficult to do.

Setting the clock manually

So let's figure out how to set our time. First of all, I'm just going to do a show clock to see what my time is, and we can see the time there. I'm going to have to set this now, because obviously it's not 1993, and I can tell you it's not 11 o'clock.

So I'm going to do a clock set, and then we're going to set this time. Actually, I'm just going to use the question mark to figure out what it's prompting me for. So it needs hours, minutes, seconds. I'm going to say, well, it is three o'clock p.m., which is 1500, and it is 45, and then I'll just give it a second.

Then I can see that it's asking for the day of the month, so this is the 12th. Oops. The 12th. And what else is it asking for, the month. I'm going to say the 12th of March. Then it's asking for the year. I'm going to say 2033. It's obviously not 2033, but we're going to enter that in.

Now when I do a show clock, we can see that the time is set to a much better time here. So there, I've set this clock.

Using an NTP server instead

This is one way of doing it. The problem is you may see a little bit of time drift with some of these machines, and more importantly, our seconds are going to be off. If we want to have logs down to the seconds, it's going to be important that all of our devices stay on the same page, that they stay on the same clock.

So we can actually set that up. We can take all of our devices and reference one single time, and to do that we set up what's called an NTP server, a Network Time Protocol server.

To do that, I'm going to go into the global config mode, so global config, and I'm going to type in NTP and I'm going to set the server. I'll hit the question mark, and now it's just asking you for either a hostname or an IP address or some sort of source.

I could have a single source on my network that goes out to the internet and syncs with the internet, and then everything syncs to that source. Or I can have all the devices synced to something out on the internet. So there are several ways I can set this up. A lot of times what I like to do is have one or two sources within my network that have an accurate time, and then everything syncs to those two times, something that's to the core of my network.

So this is how you would set up an NTP server, so that all of your devices are on the same time and you don't ever get any drift. If there's ever any drift, then it corrects itself, because it's constantly going out there and making sure that it's got the accurate time.

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