I'm currently on my fourth week of studying and on track for my long term goal of taking my CCNA exam on 6/28. I was starting to get concerned during my second week of studies because despite putting a lot of hours in I was not done with that weeks portion until the following Wednesday. In my defense the second week had almost double the content of my other study weeks but it was really demotivating to still be early in my studies, working hard, and still feeling behind. Thankfully I grinded my third week out in about 4 days and that helped get me back on track.
So what have I done so far.
During my second week Jeremy Cioara (one of the CBT Nuggets instructors) had a section using Wireshark to show the TCP/IP model in real time. Part of that section was using Wireshark to do basic network troubleshooting. For me this was my favorite part and felt very real world like something I would use at my current helpdesk job. One of the troubleshooting examples was demonstrating a DNS issue where someone reported the server as being offline but they had an old IP address cached. At work my go to when I can ping a server but someone can't resolve the address is to flush the DNS, but it was nice to have a visual of what happens in the background.
I shouldn't share a screenshot straight from the lecture but here's a quick packet capture I just took using Wireshark. As you might be able to tell I have Twitch on in the background while I'm writing this. I thought it was interesting that the Twitch streams were using TCP instead of UDP. But after some research it turns out most video streams in a browser have to be TCP unless they're using WebRTC or something else that allows UDP. Plus Twitch specifically starts multiple TCP streams and starts caching the parts of the video that are unplayed.
Basic Router/Switch configuration
After Wireshark came some practice on the CLI. I had to go through and configure the things listed below and it's something I have written out to practice from time to time.
Activating router interfaces
no domain lookups
password encryption services
Then my second favorite section, using the show commands to track down a device on the network. This also felt very real world and something I'd use on the job.
Find a MAC address
Find device using IP address
Find a device using the hostname
Then we went into PoE
I had to show one of my PoE video lessons to my coworkers because Jeremy Cioara calls out Ubiquiti for cutting corners to make their product cheaper meaning they use passive PoE at a lower voltage. This is bad because you may risk frying a device or NIC. Me and a couple of my coworkers all love Ubiquiti and use their equipment for our home networks. I did check out Ubiquiti's store and the switches I had my eyes on for future home upgrades all used active PoE and it turns out they haven't used passive PoE in about 6 years. So Jeremy was slightly out of date about that. I didn't take to heart what he said because it was in passing and mentioned casually. This is why I like Jeremy Ciora the most aside from Chuck who I've liked since before CBT. His optomistic/ighthearted and casual approach to teaching helps me get through the content. But I did have to look into his statement because I didn't want to risk running passive PoE in my home network.
Week 3 was all about subnetting. I've tried studying for the CCNA before and every time I dread the subnetting portion. I always feel like I slightly understand the math but I have no idea why I'm doing it. This is probably the first time I really understand subnetting and how to actually use that knowledge on the job. Jeremy had a section dedicated to applying that knowledge in the workplace. Subnetting is definitely not something I'd say I enjoy but it's something I can somewhat do on my own. I have a whiteboard in my office with all of the problems written out so I can practice every few days. That way I can move faster through the subnetting section of the CCNA test.
That's it for now. That's been three weeks of study since my last post. Next week is looking like VLANs, Trunking and STP.