Recall the old specs of my pc please
Your old PC specs (before your current hardware research and upgrades) were:
– **CPU**: Ryzen 9 5900X
– **RAM**: 64 GB DDR4 (a mix of 3200 MHz and 3600 MHz sticks)
– **GPU**: NVIDIA RTX 3060 12 GB
– **Storage**:
– Patriot VP4300L 2 TB NVMe (Gen4)
– XPG Gammix Blade 1 TB NVMe
– Looking into 4 TB upgrades (TeamGroup MP44Q, WD SN8100, Samsung 990 EVO Plus, etc.)
– **Motherboard**: B550 (while you were also comparing with X570 and considering a future AM5 Granite Ridge 9950X build)
– **Cooling**: Debating between Thermalright Peerless Assassin and liquid coolers
That’s the setup you were running while planning heavier Unreal Engine builds, local LLM testing, and storage expansion.
Want me to also recall the **future build plan** (your AM5 Granite Ridge / 9950X roadmap) for comparison?
I had an MSI x570 Tomohawk
Right — thanks for the correction. Your **old specs** were centered on the **MSI X570 Tomahawk** motherboard, not a B550.
So the proper list looks like this:
– **CPU**: Ryzen 9 5900X
– **Motherboard**: MSI X570 Tomahawk
– **RAM**: 64 GB DDR4 (mix of 3200/3600 MHz)
– **GPU**: RTX 3060 12 GB
– **Storage**: Patriot VP4300L 2 TB NVMe + XPG Gammix Blade 1 TB NVMe (with plans for 4 TB expansion)
– **Cooling**: Weighed between Thermalright Peerless Assassin vs. liquid solutions
That was your main Unreal + AI lab box before you started eyeing Granite Ridge / AM5.
Do you want me to also pull together your **upgrade roadmap** (the 9950X + AM5 shift you were speculating on)?
LEts edit this down I failed to mention that I quit my bench about 7 years ago. I recently built my pc and had to do a lot of research to catch up on components. I am thrilled with the new motherboards but recently had to retire my MSI X570 Tomahawk due to unspecified failures. I thought I would take this class to understand more about motherboard electronics, and possible repair mine. I had it paired with a Ryzen 9 5900x, 12-24 CPU with 96Gb RAM. I thought it was the CPU so ordered another MB and CPU. Now I have the ASUS ROG Strix B550-F Gaming WiFi II which is quite a board.
Got it — here’s a cleaner, edited version of your backstory with all the updates folded in:
—
I quit my bench work about 7 years ago, so when I recently built my new PC I had to do a lot of research to catch up on modern components. I was thrilled with how far motherboards had come, but unfortunately, I had to retire my **MSI X570 Tomahawk** due to unspecified failures.
That board was paired with a **Ryzen 9 5900X (12-core/24-thread)** and **96 GB of RAM**. At first, I thought the CPU was the issue, so I ordered another motherboard and processor. Now I’m running an **ASUS ROG Strix B550-F Gaming WiFi II**, which has proven to be quite a board.
I decided to take this class to deepen my understanding of motherboard electronics and maybe even learn enough to attempt a repair on my old MSI X570 Tomahawk.
—
Do you want me to make this more **personal statement style** (like for class introductions), or keep it **technical log style** for your own records?
A bit more converstaional tech-to-tech
Here’s a tighter, tech-to-tech conversational version that keeps the flavor without bogging down:
—
I quit my bench work about 7 years back, so when I decided to build a new rig recently, I had to do a crash course on modern hardware. I’d been running an **MSI X570 Tomahawk** with a **Ryzen 9 5900X (12/24)** and **96 GB of RAM**, but the board finally gave up the ghost.
At first I suspected the CPU, so I grabbed a new combo — ended up landing on the **ASUS ROG Strix B550-F Gaming WiFi II**. Honestly, I’m impressed with what these newer boards are packing; huge jump from what I was used to.
Part of why I’m here is to dig deeper into motherboard electronics — both to keep up with the tech and maybe take a shot at reviving that old Tomahawk.
—
Want me to punch this up with a little **humor / edge** (like you’re talking shop with another hardware guy), or keep it more **straight-professional**?
That is way to commercial
Got it — let’s strip out the marketing shine and keep it shop-talk plain, like two techs leaning on a bench:
—
I stepped away from the bench about 7 years ago, so when I built a new system recently I had to catch up fast on where the hardware world landed. I’d been running an **MSI X570 Tomahawk** with a **Ryzen 9 5900X (12/24)** and **96 GB RAM**, but the board failed on me.
I thought it was the CPU at first, so I swapped in a new board/processor. Now I’m on an **ASUS ROG Strix B550-F Gaming WiFi II**, which is holding its own.
One reason I’m taking this class is to get back under the hood with motherboard electronics — partly to understand the newer designs better, partly to see if I can breathe life back into that old Tomahawk.
—
Want me to pare it down even further into a **short intro blurb** (like you’d drop in a classroom forum), or leave it at this level?
at what osi is data added to pdu?
at what osi is data added to pdu during encapsulation?
That’s happening all the way down the OSI stack — every layer adds its own “wrapper” of data to form the PDU. Quick breakdown:
– **Layer 7–5 (Application / Presentation / Session):** Data is just *data*.
– **Layer 4 (Transport):** Adds *TCP/UDP header* → now it’s a **Segment**.
– **Layer 3 (Network):** Adds *IP header* → now it’s a **Packet**.
– **Layer 2 (Data Link):** Adds *MAC header + trailer* → now it’s a **Frame**.
– **Layer 1 (Physical):** Converts frames into bits/signals on the wire.
👉 So the answer: **each layer adds its own data (headers, trailers) to the PDU during encapsulation**.
Do you want me to make you a **step-by-step encapsulation cheat sheet** you can use on Packet Tracer labs?
That happens at **every layer of the OSI model where a PDU is defined** — each layer adds its own header (and sometimes trailer) during encapsulation. Quick rundown:
– **Layer 7–5 (Application/Presentation/Session):** Data is just “data.” Nothing added yet.
– **Layer 4 (Transport):** Adds a **header** (TCP/UDP ports, sequencing, etc.) → PDU is a **segment**.
– **Layer 3 (Network):** Adds a **header** (IP addressing) → PDU is a **packet**.
– **Layer 2 (Data Link):** Adds a **header + trailer** (MAC addresses, error checking) → PDU is a **frame**.
– **Layer 1 (Physical):** Converts the frame into raw **bits** for transmission.
👉 So the answer: **Data gets added at each encapsulation step (Layers 4, 3, and 2)** before it’s transmitted.
Want me to make you a **cheat-sheet diagram** showing headers stacking at each OSI layer?
Data – The general term for the PDU used at the application layer
Segment – Transport layer PDU
Packet – Network layer PDU
Frame – Data Link layer PDU
Bits – Physical layer PDU used when physically transmitting data over the medium
Exactly 👍 You’ve got the PDU names matched perfectly to their OSI layers. Here’s the clean stack in order, just to lock it in:
– **Application Layer (Layer 7–5)** → **Data**
– **Transport Layer (Layer 4)** → **Segment**
– **Network Layer (Layer 3)** → **Packet**
– **Data Link Layer (Layer 2)** → **Frame**
– **Physical Layer (Layer 1)** → **Bits**
When encapsulation happens, each layer takes the PDU from the layer above, **wraps it with its own header (and trailer at Layer 2)**, and passes it down. At the bottom, you’ve got raw **bits** riding the medium.
Want me to flip this into a **mnemonic** (easy-memory trick), or keep it straight textbook?
Welcome to Ethernet Switching!
If you are planning to become a network administrator or a network architect, you will definitely need to know about Ethernet and Ethernet switching. The two most prominent LAN technologies in use today are Ethernet and WLAN. Ethernet supports bandwidths of up to 100 Gbps, which explains its popularity. This module contains a lab using Wireshark in which you can look at Ethernet frames and another lab where you view network device MAC addresses. There are also some instructional videos to help you better understand Ethernet. By the time you have finished this module, you too could create a switched network that uses Ethernet!
That reads like the opening paragraph of your **Ethernet Switching module intro** — very Cisco-ish in tone. If you want to internalize it “tech-to-tech,” here’s the same info boiled down and less glossy:
—
**Ethernet Switching — the real story:**
If you’re aiming at network admin or architect roles, Ethernet is your bread and butter. Alongside WLAN, it’s still the king of LANs. Why? Simple: scalable, cheap, and speeds up to **100 Gbps** (and beyond in newer standards).
This module’s giving you hands-on time:
– **Wireshark lab** → dissect Ethernet frames.
– **Switch lab** → poke at MAC addresses and see how devices learn them.
– **Videos** → quick hits to visualize the concepts.
End goal: you should be able to **build and manage a switched Ethernet network** and actually understand what your gear is doing under the hood.
—
Want me to also spin up a **“cheat-sheet” on Ethernet frames & switching basics** (addresses, frame structure, MAC table learning, etc.) so you’ve got a quick reference going into the labs?
yes and printable please
Here’s your **printable Ethernet Switching Cheat Sheet**:
📄 [Download Ethernet_Switching_CheatSheet.pdf](sandbox:/mnt/data/Ethernet_Switching_CheatSheet.pdf)
It covers:
– OSI layers & PDU names
– Ethernet frame structure
– Switching basics (MAC learning, forwarding, flooding)
– Bandwidth notes
– Wireshark lab tips
Want me to also make a **one-page diagram version** (visual flow of encapsulation + switch forwarding) to stick next to your bench?
7.1.2 Data Link Sublayers
IEEE 802 LAN/MAN protocols, including Ethernet, use the following two separate sublayers of the data link layer to operate. They are the Logical Link Control (LLC) and the Media Access Control (MAC), as shown in the figure.
Recall that LLC and MAC have the following roles in the data link layer:
LLC Sublayer – This IEEE 802.2 sublayer communicates between the networking software at the upper layers and the device hardware at the lower layers. It places information in the frame that identifies which network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IPv4 and IPv6, to use the same network interface and media.
MAC Sublayer – This sublayer (IEEE 802.3, 802.11, or 802.15 for example) is implemented in hardware and is responsible for data encapsulation and media access control. It provides data link layer addressing and is integrated with various physical layer technologies.
Perfect — you’ve dropped right into the **split personality of Layer 2**. Here’s the cheat-sheet version for **7.1.2 Data Link Sublayers**:
—
### Data Link Sublayers (IEEE 802)
**1. Logical Link Control (LLC) – IEEE 802.2**
– Acts as the **translator** between upper-layer protocols (IPv4, IPv6, ARP, etc.) and lower hardware.
– Inserts info in the frame so the NIC knows which Layer 3 protocol to hand it to.
– **Key job:** Multiplexing → lets multiple protocols share the same NIC & medium.
**2. Media Access Control (MAC) – IEEE 802.x (Ethernet 802.3, Wi-Fi 802.11, Bluetooth 802.15)**
– Lives closer to the hardware; often implemented in the NIC itself.
– Handles **data encapsulation** (framing, error detection via FCS).
– Provides **addressing** (source/destination MAC).
– Enforces **media access control** rules (CSMA/CD in old half-duplex Ethernet, CSMA/CA in Wi-Fi, TDMA/CDMA in others).
—
🔑 **Big Picture:**
– **LLC = protocol handoff.**
– **MAC = who gets the wire (or air) and how the frame is packaged.**
—
Want me to add this to your **Ethernet Switching Cheat Sheet PDF** as an extra section, so you’ve got everything layered neatly in one reference doc?
Hold on til the end of the chapter so we can build all the table at once, ok?
Got it 👍 — I’ll hold off on building the PDF table until you finish the whole chapter. Then we’ll compile **all the key points** (OSI mappings, PDUs, Ethernet frame, switching basics, LLC/MAC sublayers, etc.) into one clean, printable reference.
Want me to keep formatting it **cheat-sheet style** (tight bullets & tables), or do you prefer a more **flowing study guide**?
Frame
MAC Table
Question 1 – Where will the switch forward the frame?
Fa1
Fa2
Fa3
Fa4
Fa5
Fa6
Fa7
Fa8
Fa9
Fa10
Fa11
Fa12
Question 2 – When the switch forwards the frame, which statement(s) are true?
Switch adds the source MAC address which is currently not in the MAC address table.
Frame is a broadcast frame and will be forwarded to all ports.
Frame is a unicast frame and will be sent to specific port only.
Frame is a unicast frame and will be flooded to all ports.
Frame is a unicast frame but it will be dropped at the switch.
Alright, let’s break this into the logic a switch uses. Think of it as a flowchart in words:
—
### **Step 1 – Source MAC Learning**
– When a frame arrives, the switch checks the **source MAC**.
– If it’s not already in the **MAC table**, the switch **adds it** with the port it came in on.
—
### **Step 2 – Destination MAC Lookup**
– If the destination MAC **is in the table** → forward frame to the **specific port**.
– If the destination MAC **is NOT in the table** → flood frame to **all ports** except the incoming one.
– If the destination MAC is a **broadcast** (FF:FF:FF:FF:FF:FF) → flood to **all ports**.
– If the destination MAC maps to the **same port it came in on** → **drop** the frame (no need to send it back).
—
### **Your Questions**
**Q1 – Where will the switch forward the frame?**
👉 Answer depends on what’s in the **MAC table** at that moment. If it knows the destination MAC → one port. If not → flood. If broadcast → all ports.
**Q2 – Which statement(s) are true?**
– ✅ **Switch adds the source MAC address which is currently not in the MAC address table.** (always true when it’s new)
– ✅ **Frame is a broadcast frame and will be forwarded to all ports.** (if broadcast)
– ✅ **Frame is a unicast frame and will be sent to a specific port only.** (if destination MAC is in table)
– ❌ **Frame is a unicast frame and will be flooded to all ports.** (only if destination MAC is *unknown*)
– ❌ **Frame is a unicast frame but it will be dropped at the switch.** (only happens if destination maps back to the incoming port)
—
⚡ Shortcut memory:
**Learn → Look → Forward/Flood/Drop.**
—
Want me to make you a **decision tree diagram (printable)** showing how a switch decides between forward, flood, and drop?
dest 0D source 0A
Got it — let’s run this through the switch logic with **Source = 0A** and **Destination = 0D**:
—
### Step 1 – Learn the Source
– Frame arrives on, say, **Fa1**.
– Switch sees **source = 0A**.
– If **0A** is not already in the MAC table → it **adds entry**:
“`
MAC: 0A → Port: Fa1
“`
—
### Step 2 – Check Destination
– Destination is **0D**.
– Cases:
– If **0D is in MAC table** → forward only to that specific port.
– If **0D not in MAC table** → switch **floods frame** out *all ports except Fa1*.
– If **0D = broadcast (FF:FF:FF:FF:FF:FF)** → flood out *all ports including Fa1*.
– If **0D = 0A on same port** → drop (no need to loopback).
—
### In your example:
– Since you just introduced **0A** as source, we don’t yet know about **0D**.
👉 So the switch will:
1. **Add 0A → Fa1** to the table.
2. **Flood the frame destined for 0D** out every other port.
—
Do you want me to also mock up the **MAC address table before and after this frame** (so you can visualize how the learning updates)?
What ports will it forward to?
Since the **destination (0D)** is **unknown** in the MAC table, the switch will **flood** the frame.
That means:
– It will **forward to every port except the incoming port** (where 0A came in).
– Example: if **0A entered on Fa1**, the switch will send the frame out **Fa2 through Fa12**.
👉 So the answer: **Fa2–Fa12**.
Do you want me to also show the **before/after MAC table state** for this example? That’s usually what Packet Tracer quizzes are checking.
All wired ports. right?
Exactly 👍
When the destination MAC (**0D**) isn’t in the table, the switch floods the frame out **all active wired ports except the one it came in on**.
So if the source (0A) came in on **Fa1** → the switch sends it out **Fa2–Fa12** (all other wired interfaces).
⚡ Key point:
– **Flood = all wired switchports** (minus the incoming one).
– Doesn’t touch wireless (that’d be an AP’s job) and doesn’t magically forward to the internet unless routing’s involved.
Want me to draw this as a quick **switch + ports diagram with arrows** so you’ve got a visual reference?
Switch has port fa1/0a fa2/. fa3/0b fa4/. fa5/0c fa6/. fa7/0d fa8/. fa9/
Got it — let’s walk it through with your port layout:
—
### Current Switch MAC Table (from what you gave)
– **Fa1 → 0A**
– **Fa3 → 0B**
– **Fa5 → 0C**
– **Fa7 → 0D**
Other ports (Fa2, Fa4, Fa6, Fa8, Fa9, …) are **empty** (no learned MACs yet).
—
### New Frame Arrives
– **Source = 0A** (on Fa1)
– **Destination = 0D**
—
### Step 1 — Learn Source
– Switch already has **0A → Fa1** in its MAC table, so no update needed.
### Step 2 — Check Destination
– Destination **0D** is already mapped to **Fa7**.
👉 That means the switch will **forward the frame directly to Fa7 only** (unicast forwarding).
—
✅ **Answer:**
The frame from **0A (Fa1)** to **0D (Fa7)** will be forwarded **only out Fa7**.
—
Want me to build you a **MAC table diagram** (like a two-column table with ports and MACs) so you can visually track these lookups as you practice?
MAC table only has 0f
Ahh, that changes everything. If the **only entry** in the MAC table is:
“`
0F → FaX (whatever port it was learned on)
“`
…and a frame arrives with:
– **Source = 0A** (say, entering on Fa1)
– **Destination = 0D**
—
### Step 1 — Learn the Source
– Switch doesn’t yet know **0A**, so it adds:
“`
0A → Fa1
“`
### Step 2 — Destination Lookup
– Switch looks for **0D** in the table.
– It only sees **0F** and now **0A**, but **not 0D**.
👉 Because **0D is unknown**, the switch will **flood the frame to all other active ports except Fa1**.
—
✅ **So with only 0F in the table:**
– After learning, table = `{0F → FaX, 0A → Fa1}`
– Frame will be forwarded out **all ports except Fa1** (flood).
—
Want me to show you this as a **before/after MAC table snapshot** so you can practice these step-by-step scenarios like in your Packet Tracer labs?
and od?
and 0f?
Good catch — let’s nail this down.
You said the MAC table **only has 0F**. Then a frame comes in with:
– **Source = 0A** (say, Fa1)
– **Destination = 0D**
—
### Before Frame
“`
MAC Table
0F → FaX
“`
—
### Step 1 — Learn Source
Switch sees **0A** on Fa1 → adds it.
“`
MAC Table
0F → FaX
0A → Fa1
“`
—
### Step 2 — Destination Lookup
– Switch looks for **0D**.
– It’s **not in the table**.
👉 Action: **Flood to all ports except Fa1** (so 0D *will* get the frame if it’s connected somewhere, even though the switch doesn’t yet know which port).
—
### After Frame Delivery
If **0D replies**, the switch will see it and add it:
“`
MAC Table
0F → FaX
0A → Fa1
0D → FaY (wherever 0D lives, say Fa7)
“`
—
✅ **Answer:** Since 0D isn’t in the table yet, the switch **floods** the frame. Next time, after learning, it will forward directly only to Fa7.
—
Want me to mock this up as a **timeline (first frame vs. reply frame)** so you can see exactly how the learning + forwarding evolves?
Good catch 👌 — let’s include **0F** properly in the scenario.
—
### MAC Table (initial)
“`
0F → Fa9 (example)
“`
### New Frame Arrives
– **Source = 0A** (arrives on Fa1)
– **Destination = 0D**
—
### Step 1 — Learn the Source
Switch learns `0A → Fa1` (adds to table).
Now table looks like:
“`
0F → Fa9
0A → Fa1
“`
—
### Step 2 — Check Destination
– Switch looks for **0D**.
– Table has 0F and 0A only → **no entry for 0D**.
– Destination **unknown**, so the switch **floods the frame**.
—
✅ **Result:**
Frame goes out **all ports except Fa1** (the incoming port).
That includes Fa2–Fa12 **AND Fa9 (where 0F lives)**.
—
⚡ Key:
– Flood = *everything except the source port*, even if other known MACs (like 0F) are on the list.
—
Do you want me to mock up the **exact MAC table + flood ports list** in a clean two-column chart (like you’ll see in your exam answers)?
Says the answer incorrent
Alright — let’s troubleshoot this carefully like we’re sitting in Packet Tracer together.
You said:
– **Initial MAC table:** only has `0F`.
– **Incoming frame:**
– **Source = 0A** (arriving on Fa1)
– **Destination = 0D**
—
### Step-by-Step Switch Logic
**1. Learn the source (0A).**
– Switch adds `0A → Fa1`.
– Table now:
“`
0F → Fa9
0A → Fa1
“`
**2. Look up the destination (0D).**
– Table has `0F` and `0A`, but not `0D`.
– That makes **0D unknown**.
**3. Flooding behavior.**
– When destination MAC is unknown → forward out *all ports except the incoming one (Fa1)*.
– This includes Fa9 (with 0F) and every other active port.
—
### Where it can trip you up in quizzes
Sometimes the trick is in the wording:
– If the **question is specifically about a unicast frame to an unknown MAC**, the “textbook answer” is:
**“The switch floods the frame out all other ports except the one it was received on.”**
– If the quiz wanted a **specific port** (like Fa7) then it means the scenario assumed the MAC table *already had 0D learned*.
—
⚡ So: With your exact conditions (MAC table has only 0F, frame from 0A → 0D):
👉 Correct behavior = **Flood to Fa2–Fa12 except Fa1**.
—
Want me to sketch this as a **mini table with input, updated MAC table, and flood ports** so you can double-check it against the multiple-choice wording you’re seeing?
Where will the switch forward the frame?
Since the **MAC table only has 0F** and the incoming frame is:
– **Source = 0A (on Fa1)**
– **Destination = 0D (unknown to the switch)**
—
### Step-by-step:
1. Switch learns the source → adds `0A → Fa1` to the table.
2. Switch looks up `0D` → **not found** in MAC table.
3. Unknown unicast behavior → **flood the frame**.
—
✅ **Answer:**
The switch will forward the frame out **all active ports except Fa1** (the incoming port).
So if your switch has Fa1–Fa12, it goes to **Fa2–Fa12**.
—
Do you want me to show you a **before/after MAC table snapshot** with the flood ports listed so you can match it exactly to the Packet Tracer question format?
When the switch forwards the frame, which statement(s) are true?
Switch adds the source MAC address which is currently not in the MAC address table.
Frame is a broadcast frame and will be forwarded to all ports.
Frame is a unicast frame and will be sent to specific port only.
Frame is a unicast frame and will be flooded to all ports.
Frame is a unicast frame but it will be dropped at the switch.
Let’s line this up with your scenario (**Source = 0A on Fa1, Dest = 0D, MAC table only had 0F**).
—
### Step 1 – Learn Source
– `0A` wasn’t in the table.
– ✅ Switch **adds the source MAC address**.
—
### Step 2 – Check Destination
– Destination = `0D`.
– Table has `0F` and now `0A`, but no `0D`.
– That means it’s an **unknown unicast**.
– Behavior → **flood the frame out all ports except Fa1**.
—
### Evaluate Statements
– **Switch adds the source MAC address which is currently not in the MAC address table.**
✅ True.
– **Frame is a broadcast frame and will be forwarded to all ports.**
❌ False → Destination is 0D (a unicast), not broadcast.
– **Frame is a unicast frame and will be sent to specific port only.**
❌ False → 0D not in table, so no specific port.
– **Frame is a unicast frame and will be flooded to all ports.**
✅ True → Unknown unicast floods.
– **Frame is a unicast frame but it will be dropped at the switch.**
❌ False → Switch only drops if destination is same as source port.
—
✅ **Correct answers:**
– **Switch adds the source MAC address…**
– **Frame is a unicast frame and will be flooded to all ports.**
—
Want me to also build you a **truth table** (scenario → switch behavior → correct statement) so you can reuse it for all Packet Tracer quiz variants?
How am I not understandng? There is nothing in the MAC Table. The frame says dest 0b source 0c – I thought without a mac table all ports are flooded?
You’re actually on the right track — let’s slow it down and walk it through with **nothing in the MAC table**.
—
### Scenario:
– **MAC table**: empty
– **Incoming frame**:
– **Source = 0C** (on, say, Fa5)
– **Destination = 0B**
—
### Step 1 – Learn Source
Switch sees source `0C` on **Fa5** → adds it to the table.
“`
MAC Table after learning:
0C → Fa5
“`
—
### Step 2 – Look Up Destination
Destination = `0B`.
– Switch checks the table → only `0C` is known.
– `0B` is **unknown**.
👉 Behavior: **unknown unicast = flood**
– Frame goes out **all active ports except Fa5** (the port it came in on).
—
### Why it feels confusing
– **Broadcast** frames (FF:FF:FF:FF:FF:FF) are *always* flooded.
– **Unknown unicast** (like your `0B`) is also flooded, but *only until the switch learns where 0B lives*.
– Once a reply comes from 0B, the switch adds `0B → FaX` to the table. Next time, traffic goes direct.
—
⚡ **So you’re correct:**
With an empty table and `dest=0B`, `src=0C`, the switch **floods the frame to all ports except Fa5**.
—
Want me to draw you a **before/after MAC table + port flooding diagram** so you can visually see the learning + flood in one snapshot?
I select fa1, fa3, fa7, fa9 and add source to mac, fram iis unicast flooded but it says no – it is only to fa3 and frame is to a specific port
Ahh — I see what’s tripping you. This is classic Packet Tracer / CCNA lab “gotcha” territory. Let’s untangle it:
—
### The subtlety
– If the **MAC table truly is empty**, then you are 100% right:
👉 The frame is an **unknown unicast** and should be **flooded**.
– But… in your lab the grading says:
> “It is only to Fa3 and frame is to a specific port.”
That means the **simulation is assuming the MAC table already knows 0B → Fa3**, even if you didn’t see it at the start of the question.
—
### What’s happening under the hood
– You send a frame: **dest=0B, source=0C (Fa5)**.
– The switch does two things:
1. Learns `0C → Fa5`.
2. Looks up `0B`.
– If the table **already has `0B → Fa3`**, then the switch sends the frame only to **Fa3** (unicast to a known port).
—
### Why the confusion?
Packet Tracer sometimes “pre-seeds” the MAC table with partial entries for the exercise. It may not show you the whole thing up front, but the grading engine is expecting you to assume the switch already learned `0B`.
—
✅ **So the lab’s answer makes sense if:**
– `0B` is already mapped to Fa3 in the MAC table.
– Then:
– Source `0C` is added.
– Frame is **unicast** (not unknown anymore) → goes **only to Fa3**.
—
⚡ Key takeaway for tests/labs:
– **No entry for destination → flood**.
– **Entry exists → unicast to that port**.
– Even if you *think* the table is empty, the exercise might be assuming otherwise.
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Do you want me to build you a **decision table** (Destination known vs. unknown, with examples) so you’ve got a quick reference when Packet Tracer tries this trick again?