We've finally arrived at our last section, UDP Service Issues.
While both TCP and UDP rely on services to operate,
in my experience, UDP is more often afflicted by service‑related issues.
The top three services that I have encountered the most issues with are DHCP,
DNS, and NTP.
Restarting the service allows the process to clear its memory and
start fresh without bringing the whole system down.
Services often fail due to something being incorrectly configured,
and more often than not, the misconfiguration requires no human intervention.
Something became unstable during the normal course of operation.
A good example of this is DHCP assigning duplicate IP
addresses to multiple machines.
If you're dealing with a UDP issue and you're sure it's not a firewall issue,
the service itself may be to blame.
Let's drop to one final video to show the outcome of restarting a service.
We're now successfully connected to a router.
Let's see what addresses we currently have leased out.
As you can see,
we currently have the address of 192.168.1.100 leased out. Now let's
say we get a call from the CEO, and the CEO states that he is unable
to get an address from the wireless.
You, as the network engineer, verify that this is not a firewall issue.
At this point,
you decide it's best to restart the service. With the service restarted,
let's see if any of our addresses are currently leased out.
Okay, it looks good as nothing is currently connected.
Let's connect a couple of devices and see if that made a difference.
Awesome.
We now have two devices in our DHCP pool.
All that it needed to fix the issue was a quick service reboot.
And even better yet, the CEO is really happy.
I do want to make a quick side note though. As with our prior example,
this demo shown was just to give you a rough idea on service restarts. But the commands and actual syntax will vary wildly between vendors.