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Module 22
VLAN Trunking Protocol (VTP)
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# 📘 CCNA 200-301 - Video 22: VLAN Trunking Protocol (VTP) ## Deep Study Notes --- ## 📌 Learning Objectives By the end of this video, you should understand: - What VTP is and why it's used - VTP modes (Server, Client, Transparent, Off) - VTP versions (1, 2, 3) - VTP pruning - VTP configuration and verification - VTP troubleshooting and best practices --- ## 🧠 Core Concepts ### 1. What is VTP? **Definition:** VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that synchronizes VLAN information across a network of interconnected switches. It allows you to create, delete, and manage VLANs centrally from a single switch. **Analogy:** Think of VTP like a master blueprint for a building. One architect (VTP Server) creates the blueprint (VLAN database). All construction crews (VTP Clients) receive the same blueprint and build accordingly. If you need to change the design, you update the master blueprint once, and everyone gets the update. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITHOUT VTP (Manual VLAN Management) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B Switch C │ │ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ │ │ │ VLAN 10 │ │ VLAN 10 │ │ VLAN 10 │ │ │ │ VLAN 20 │ │ VLAN 20 │ │ VLAN 20 │ │ │ │ VLAN 30 │ │ VLAN 30 │ │ VLAN 30 │ │ │ └─────────────┘ └─────────────┘ └─────────────┘ │ │ │ │ To add VLAN 40: │ │ • Configure on Switch A: create VLAN 40 │ │ • Configure on Switch B: create VLAN 40 │ │ • Configure on Switch C: create VLAN 40 │ │ • Time-consuming, error-prone │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITH VTP (Centralized VLAN Management) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────────────┐ │ │ │ VTP Server │ │ │ │ Switch A │ │ │ │ VLAN 10, 20, 30 │ │ │ └───────────┬─────────────┘ │ │ │ │ │ ┌───────────┼───────────┐ │ │ │ │ │ │ │ ┌─────▼─────┐ ┌───▼────┐ ┌────▼─────┐ │ │ │ Switch B │ │Switch C│ │ Switch D │ │ │ │ VTP Client│ │VTP Client││VTP Client│ │ │ └───────────┘ └─────────┘ └──────────┘ │ │ │ │ To add VLAN 40: │ │ • Configure only on Switch A (VTP Server) │ │ • All client switches automatically learn VLAN 40 │ │ • Fast, consistent, centralized management │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 2. VTP Components | Component | Description | |-----------|-------------| | **VTP Domain** | Group of switches with same domain name that share VLAN information | | **VTP Revision Number** | Incremented with each VLAN change; used to determine most recent update | | **VTP Password** | Optional; must match across all switches in domain | | **VTP Pruning** | Prevents unnecessary broadcast traffic across trunks | | **VTP Advertisement** | Messages sent every 5 minutes or when changes occur | **VTP Domain Rules:** - All switches must have the same domain name to share VLANs - All switches must have the same VTP password (if configured) - The switch with the highest revision number dominates - Adding a switch with a higher revision number can overwrite VLAN database! --- ### 3. VTP Modes | Mode | VLAN Creation | VLAN Storage | VLAN Propagation | VTP Advertisements | |------|---------------|--------------|------------------|-------------------| | **Server** | Yes | vlan.dat | Yes (forward) | Sends and receives | | **Client** | No | vlan.dat (read-only) | Yes (forward) | Sends and receives | | **Transparent** | Yes | Running-config | No (forward only) | Forwards but doesn't use | | **Off** | Yes | Running-config | No | Disabled | ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VTP MODES COMPARISON │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ VTP SERVER: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Default mode (default domain = null) │ │ │ │ • Can create, modify, delete VLANs │ │ │ │ • Stores VLANs in vlan.dat │ │ │ │ • Sends and forwards VTP advertisements │ │ │ │ • Recommended: 1-2 switches per domain │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ VTP CLIENT: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Cannot create, modify, delete VLANs │ │ │ │ • Stores VLANs in vlan.dat (read-only) │ │ │ │ • Sends and forwards VTP advertisements │ │ │ │ • Learns VLANs from VTP Server │ │ │ │ • Recommended: All other switches │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ VTP TRANSPARENT: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Can create, modify, delete VLANs locally │ │ │ │ • Stores VLANs in running-config (not vlan.dat) │ │ │ │ • Forwards VTP advertisements but does NOT use them │ │ │ │ • Revision number always 0 │ │ │ │ • Recommended: When mixing vendors, or when manual VLAN control needed│ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ VTP OFF: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Same as Transparent but does not forward VTP messages │ │ │ │ • Most secure option (VTP completely disabled) │ │ │ │ • Recommended: Best practice for most networks │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 4. VTP Versions | Feature | VTPv1 | VTPv2 | VTPv3 | |---------|-------|-------|-------| | **VLAN Range** | 1-1005 | 1-1005 | 1-4094 | | **Token Ring Support** | Yes | Yes | No | | **Password Encryption** | No | No | Yes (with hidden mode) | | **VLAN Consistency Check** | Yes | No (improved) | Enhanced | | **Extended VLAN Support** | No | No | Yes (1006-4094) | | **Private VLAN Support** | No | No | Yes | | **MST Support** | No | No | Yes | | **Multiple Domain Support** | No | No | Yes | **VTP Version Comparison:** | Version | Key Features | |---------|--------------| | **VTPv1** | Original version, basic VLAN management | | **VTPv2** | Added Token Ring support, improved consistency checking | | **VTPv3** | Extended VLANs, password encryption, private VLANs, MST support | --- ### 5. VTP Revision Number **Critical Concept:** The VTP revision number is the most important and dangerous aspect of VTP. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VTP REVISION NUMBER │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ How Revision Number Works: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Starts at 0 │ │ │ │ • Increments by 1 each time a VLAN change is made on a Server │ │ │ │ • Higher revision number = more recent configuration │ │ │ │ • Switches accept configuration from switches with higher revision │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ DANGER: Adding a Switch with Higher Revision Number │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ Production Network New Switch (ex-lab) │ │ │ │ Revision: 5 Revision: 100 │ │ │ │ VLANs: 10, 20, 30 VLANs: (empty) │ │ │ │ │ │ │ │ When connected: │ │ │ │ • New switch has higher revision (100 > 5) │ │ │ │ • Production switches accept the higher revision │ │ │ │ • Production switches DELETE all VLANs! │ │ │ │ • Network outage! │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ PREVENTION: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Always reset revision number on switches before adding to network │ │ │ │ Switch(config)# vtp mode transparent │ │ │ │ Switch(config)# vtp mode server │ │ │ │ (Changing mode resets revision to 0) │ │ │ │ │ │ │ │ • Use VTP password (prevents unauthorized changes) │ │ │ │ • Use VTP version 3 with hidden mode (encrypted passwords) │ │ │ │ • Set all switches to VTP transparent or off (best practice) │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 6. VTP Pruning **Definition:** VTP pruning prevents unnecessary broadcast and unknown unicast traffic from being flooded across trunks where no active ports exist in that VLAN. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VTP PRUNING │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ WITHOUT PRUNING: │ │ │ │ VLAN 10 VLAN 10 VLAN 10 │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ Switch A│────Trunk────────│ Switch B│───Trunk────────│ Switch C│ │ │ │ Ports: │ │ Ports: │ │ Ports: │ │ │ │ Fa0/1 │ │ (none) │ │ (none) │ │ │ │ (VLAN10)│ └─────────┘ └─────────┘ │ │ └─────────┘ │ │ │ │ Broadcast from VLAN 10 → Flooded to Switch B → Flooded to Switch C │ │ (wastes bandwidth on links where no VLAN 10 ports exist) │ │ │ │ WITH PRUNING: │ │ │ │ VLAN 10 VLAN 10 VLAN 10 │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ Switch A│────Trunk────────│ Switch B│───Trunk────────│ Switch C│ │ │ │ Ports: │ │ Ports: │ │ Ports: │ │ │ │ Fa0/1 │ │ (none) │ │ (none) │ │ │ │ (VLAN10)│ └─────────┘ └─────────┘ │ │ └─────────┘ │ │ │ │ Broadcast from VLAN 10 → Stopped at Switch B (no VLAN 10 ports) │ │ (Bandwidth saved) │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **Pruning Configuration:** ```cisco ! Enable VTP pruning globally (on VTP Server only) Switch(config)# vtp pruning ! Verify pruning Switch# show vtp status Switch# show interfaces trunk ``` --- ### 7. VTP Configuration **Basic VTP Configuration (Server):** ```cisco ! Configure VTP domain and mode SwitchA> enable SwitchA# configure terminal ! Set VTP mode (must be done before domain to clear revision) SwitchA(config)# vtp mode server ! Set VTP domain name SwitchA(config)# vtp domain LAB ! Set VTP password (optional but recommended) SwitchA(config)# vtp password Cisco123 ! Set VTP version SwitchA(config)# vtp version 2 ! Enable pruning (optional) SwitchA(config)# vtp pruning ! Verify configuration SwitchA# show vtp status ``` **Basic VTP Configuration (Client):** ```cisco ! Configure VTP client SwitchB> enable SwitchB# configure terminal ! Set VTP mode SwitchB(config)# vtp mode client ! Set VTP domain name (must match server) SwitchB(config)# vtp domain LAB ! Set VTP password (must match server) SwitchB(config)# vtp password Cisco123 ! Set VTP version (must match server) SwitchB(config)# vtp version 2 ! Verify SwitchB# show vtp status ``` **VTP Transparent Configuration:** ```cisco ! Configure VTP transparent SwitchC> enable SwitchC# configure terminal ! Set VTP mode transparent SwitchC(config)# vtp mode transparent ! Optional: Set domain (not required but recommended for organization) SwitchC(config)# vtp domain LAB ! Verify SwitchC# show vtp status ``` **VTP Off Configuration (Best Practice):** ```cisco ! Configure VTP off SwitchD> enable SwitchD# configure terminal ! Set VTP mode off SwitchD(config)# vtp mode off ! Verify SwitchD# show vtp status ``` --- ### 8. VTP Configuration (Version 3) **VTPv3 Configuration:** ```cisco ! Configure VTP version 3 Switch(config)# vtp version 3 ! Set VTP mode Switch(config)# vtp mode server ! Set VTP domain Switch(config)# vtp domain LAB ! Set primary server (VTPv3 requires primary server election) Switch# vtp primary-server ! Configure hidden password (encrypted) Switch(config)# vtp password Cisco123 hidden ! Verify Switch# show vtp status Switch# show vtp password ``` --- ### 9. VTP Verification Commands | Command | Purpose | |---------|---------| | `show vtp status` | Display VTP status, revision number, domain, mode | | `show vtp password` | Display VTP password (if configured) | | `show vtp counters` | Display VTP statistics | | `show vtp interface` | Display VTP-enabled interfaces | | `show vlan brief` | Display VLANs (to verify VTP propagation) | **Example Outputs:** ```cisco Switch# show vtp status VTP Version capable : 1 to 3 VTP version running : 2 VTP Domain Name : LAB VTP Pruning Mode : Enabled VTP Traps Generation : Disabled Device ID : 001a.2b3c.4d5e Configuration last modified by : 192.168.1.1 at 3-1-24 10:30:45 Local updater ID is 192.168.1.1 on interface Gi0/0 (first VLAN interface found) Feature VLAN: -------------- VTP Operating Mode : Server Maximum VLANs supported locally : 1005 Number of existing VLANs : 25 Configuration Revision : 15 MD5 Digest : 0x12 0x34 0x56 0x78 0x9A 0xBC 0xDE 0xF0 0x12 0x34 0x56 0x78 0x9A 0xBC 0xDE 0xF0 Switch# show vtp counters VTP statistics: Summary advertisements received : 150 Subset advertisements received : 25 Request advertisements received : 5 Summary advertisements transmitted : 200 Subset advertisements transmitted : 35 Request advertisements transmitted : 2 Number of config revision errors : 0 Number of config digest errors : 0 Number of VTP version 2 errors : 0 VTP pruning statistics: Trunk Join Transmitted Join Received Summary advts received from non-pruning-capable device ---------------- ----------------- ---------------- ---------------------------- GigabitEthernet0/1 15 12 0 GigabitEthernet0/2 10 8 0 ``` --- ### 10. VTP Troubleshooting | Problem | Symptom | Solution | |---------|---------|----------| | **Client Not Learning VLANs** | `show vlan` shows only default VLANs | Verify domain name, password, version match | | **VLANs Disappeared** | All VLANs lost after adding a switch | A switch with higher revision number overwrote database | | **VTP Not Working** | No advertisements exchanged | Check trunk status between switches | | **Password Mismatch** | VTP status shows "disabled" | Verify password matches on all switches | | **Version Mismatch** | VTP not synchronizing | All switches must run same version | **Common Troubleshooting Steps:** ```cisco ! Step 1: Check VTP status Switch# show vtp status ! Step 2: Verify domain name Switch# show vtp status | include Domain ! Step 3: Check revision number Switch# show vtp status | include Revision ! Step 4: Verify trunk status Switch# show interfaces trunk ! Step 5: Check VTP counters for errors Switch# show vtp counters ! Step 6: Reset revision number (if needed) Switch(config)# vtp mode transparent Switch(config)# vtp mode server ! This resets revision to 0 ``` --- ### 11. VTP Best Practices ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VTP BEST PRACTICES │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ RECOMMENDED: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Use VTP mode OFF or TRANSPARENT (most secure) │ │ │ │ • Always reset revision number on switches before adding to network │ │ │ │ • Use VTP password (especially with VTPv3 hidden mode) │ │ │ │ • Limit VTP Server switches to 1-2 per domain │ │ │ │ • Use VTP pruning to reduce broadcast traffic │ │ │ │ • Keep VTP version consistent across domain │ │ │ │ • Document VTP configuration │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ NOT RECOMMENDED: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Using VTP client mode on switches that need local VLANs │ │ │ │ • Adding unknown switches to production network │ │ │ │ • Relying on VTP without passwords │ │ │ │ • Multiple VTP servers without coordination │ │ │ │ • Mixing VTP versions │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ MODERN BEST PRACTICE: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ • Use VTP mode TRANSPARENT or OFF │ │ │ │ • Manage VLANs manually or with automation (Ansible, Python) │ │ │ │ • Use VTPv3 if VTP is required │ │ │ │ • Always use VTP passwords │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ## 🔧 Complete Configuration Examples ### Lab 1: Basic VTP Configuration (Server + Clients) **Topology:** ``` VTP Server VTP Client VTP Client Switch A Switch B Switch C (Server) (Client) (Client) │ │ │ └─────────────────────────┼───────────────────────┘ │ Trunk Links ``` **Switch A (VTP Server) Configuration:** ```cisco hostname SwitchA ! ! Configure VTP vtp mode server vtp domain CCNA_LAB vtp password SecureVTP123 vtp version 2 vtp pruning ! ! Create VLANs vlan 10 name Engineering ! vlan 20 name Sales ! vlan 30 name IT ! ! Configure trunk ports interface range gigabitEthernet 0/1-2 switchport mode trunk switchport trunk allowed vlan all ! end ``` **Switch B (VTP Client) Configuration:** ```cisco hostname SwitchB ! ! Configure VTP vtp mode client vtp domain CCNA_LAB vtp password SecureVTP123 vtp version 2 ! ! Configure trunk ports interface range gigabitEthernet 0/1-2 switchport mode trunk ! ! Verify VLANs received from server end ``` **Switch C (VTP Client) Configuration:** ```cisco hostname SwitchC ! ! Configure VTP vtp mode client vtp domain CCNA_LAB vtp password SecureVTP123 vtp version 2 ! ! Configure trunk ports interface range gigabitEthernet 0/1-2 switchport mode trunk ! end ``` --- ### Lab 2: VTP Transparent Mode (Local VLAN Control) **Topology:** ``` VTP Server VTP Transparent VTP Client Switch A Switch B Switch C (Server) (Transparent) (Client) VLANs: 10,20,30 Local VLAN: 100 Receives from A │ │ │ └─────────────────────────┼───────────────────────┘ │ Trunk Links ``` **Switch B (VTP Transparent) Configuration:** ```cisco hostname SwitchB ! ! Configure VTP vtp mode transparent vtp domain CCNA_LAB vtp version 2 ! ! Create local VLAN (not propagated) vlan 100 name Local_VLAN ! ! Configure trunk ports interface range gigabitEthernet 0/1-2 switchport mode trunk ! ! Access port for local VLAN interface fastEthernet 0/1 switchport mode access switchport access vlan 100 ! end ! Verify - Switch B will forward VTP advertisements but not use them ``` --- ### Lab 3: Reset VTP Revision Number ```cisco ! Step 1: Before adding switch to network, check revision Switch# show vtp status | include Revision ! If revision > 0, reset it ! Step 2: Change mode to transparent (resets revision to 0) Switch(config)# vtp mode transparent ! Step 3: Change mode back to client or server (revision remains 0) Switch(config)# vtp mode client ! Step 4: Verify revision is 0 Switch# show vtp status | include Revision ! Output: Configuration Revision: 0 ! Step 5: Now safe to add to production network ``` --- ## 📊 Text-Based Diagrams ### VTP Advertisement Flow ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VTP ADVERTISEMENT FLOW │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ VTP Server (Revision 5) │ │ │ │ │ │ Summary Advertisement (every 5 min or on change) │ │ │ - Contains domain name, revision, MD5 digest │ │ ▼ │ │ VTP Client (Revision 3) │ │ │ │ │ │ Client checks: Revision (5 > 3) → Request │ │ │ ─────────────────────────────────────► │ │ │ │ │ │ Subset Advertisement │ │ │ - Contains full VLAN database │ │ │ ◄───────────────────────────────────── │ │ │ │ │ │ Client updates local VLAN database to revision 5 │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ## ✅ Exam Tips (For CCNA 200-301) | Topic | What Cisco Tests | |-------|------------------| | **VTP Modes** | Server (creates VLANs), Client (learns VLANs), Transparent (local VLANs, forwards ads) | | **Revision Number** | Higher wins; dangerous if not reset | | **VTP Pruning** | Reduces broadcast traffic on trunks | | **VTP Versions** | v3 supports extended VLANs and encryption | | **VTP Password** | Must match across domain | | **VTP Domain** | Must match across domain | ### Common Exam Scenarios: **Scenario 1:** "A switch with VTP revision 100 is added to a network with revision 5. What happens?" - **Answer:** The new switch's higher revision overwrites the production VLAN database, potentially deleting all VLANs **Scenario 2:** "Which VTP mode can create VLANs but does not propagate them?" - **Answer:** VTP Transparent mode **Scenario 3:** "What is the purpose of VTP pruning?" - **Answer:** Prevents broadcast traffic from being flooded to switches without active ports in that VLAN ### Mnemonics: **VTP Modes:** **"SCT" - Server Creates, Client Copies, Transparent Tells but doesn't use** - **S**erver: Creates VLANs - **C**lient: Copies VLANs - **T**ransparent: Tells others but doesn't use **VTP Revision Danger:** **"Higher is Deadlier"** - Higher revision number = more recent = overwrites others --- ## 📝 Summary (1-Minute Revision) ``` VTP (VLAN Trunking Protocol): PURPOSE: ├── Centralized VLAN management across switches ├── Synchronizes VLAN database automatically └── Cisco proprietary VTP MODES: ├── Server: Create/modify/delete VLANs, propagate to others ├── Client: Receive VLAN info, cannot create/modify ├── Transparent: Local VLANs, forwards but doesn't use VTP └── Off: VTP disabled VTP REVISION NUMBER: ├── Increments with each VLAN change ├── Higher revision overwrites lower ├── DANGER: Adding switch with higher revision wipes VLANs └── Reset: Change mode to transparent then back VTP VERSIONS: ├── v1: Original, VLANs 1-1005 ├── v2: Token Ring support └── v3: Extended VLANs (1006-4094), encrypted passwords, MST support VTP PRUNING: ├── Prevents broadcast flooding to switches without VLAN ports └── Saves trunk bandwidth CONFIGURATION: ├── vtp mode [server|client|transparent|off] ├── vtp domain [name] ├── vtp password [password] ├── vtp pruning └── vtp version [1|2|3] VERIFICATION: ├── show vtp status ├── show vtp counters └── show vlan brief BEST PRACTICE: └── Use VTP transparent or off (manual VLAN management) ``` --- ## 🧪 Practice Questions **1. Which VTP mode can create, modify, and delete VLANs?** - A) Client - B) Server - C) Transparent - D) Off <details> <summary>Answer</summary> <b>B) Server</b> - Only VTP Server mode can create, modify, and delete VLANs that are propagated. </details> **2. What happens when a switch with a higher VTP revision number joins a domain?** - A) It learns the domain's VLANs - B) It overwrites the domain's VLAN database - C) It becomes the VTP server - D) It is rejected from the domain <details> <summary>Answer</summary> <b>B) It overwrites the domain's VLAN database</b> - Higher revision number is considered more recent and overwrites lower revisions. </details> **3. Which VTP mode forwards VTP advertisements but does not use them to update its VLAN database?** - A) Server - B) Client - C) Transparent - D) Off <details> <summary>Answer</summary> <b>C) Transparent</b> - Transparent mode forwards advertisements but maintains its own local VLAN database. </details> **4. What is the purpose of VTP pruning?** - A) Remove unused VLANs from the database - B) Prevent broadcast traffic from flooding to switches without active ports in that VLAN - C) Delete old VTP advertisements - D) Reduce VTP update frequency <details> <summary>Answer</summary> <b>B) Prevent broadcast traffic from flooding to switches without active ports in that VLAN</b> - VTP pruning saves trunk bandwidth. </details> **5. Which VTP version supports extended VLANs (1006-4094)?** - A) VTPv1 - B) VTPv2 - C) VTPv3 - D) All versions <details> <summary>Answer</summary> <b>C) VTPv3</b> - VTP version 3 supports extended VLAN range (1006-4094). </details> **6. Which command resets the VTP revision number to 0?** - A) `clear vtp revision` - B) `vtp reset` - C) `vtp mode transparent` then `vtp mode server` - D) `no vtp domain` <details> <summary>Answer</summary> <b>C) `vtp mode transparent` then `vtp mode server`</b> - Changing VTP mode resets the revision number. </details> **7. What must match for VTP to synchronize between switches? (Select two)** - A) VTP domain name - B) VTP password - C) Switch model - D) Interface speed <details> <summary>Answer</summary> <b>A and B</b> - VTP domain name and password must match for synchronization. </details> **8. Which VTP mode is the most secure?** - A) Server - B) Client - C) Transparent - D) Off <details> <summary>Answer</summary> <b>D) Off</b> - VTP Off completely disables VTP, eliminating any risk of accidental VLAN overwrites. </details> **9. What is the default VTP mode on a Cisco switch?** - A) Server - B) Client - C) Transparent - D) Off <details> <summary>Answer</summary> <b>A) Server</b> - Default VTP mode is Server (with no domain configured). </details> **10. What does the `vtp pruning` command do?** - A) Enables VTP pruning globally - B) Disables VTP pruning - C) Shows pruning status - D) Configures pruning on a trunk <details> <summary>Answer</summary> <b>A) Enables VTP pruning globally</b> - This command enables VTP pruning on the VTP server. </details> **11. A switch shows "VTP Operating Mode: Client" but does not have VLANs from the server. What should you check first?** - A) Trunk status - B) VTP domain name - C) VTP password - D) All of the above <details> <summary>Answer</summary> <b>D) All of the above</b> - Trunk must be up, domain name and password must match. </details> **12. Which statement about VTP transparent mode is true?** - A) It can create VLANs that are not propagated - B) It cannot create VLANs - C) It does not forward VTP advertisements - D) It uses vlan.dat for storage <details> <summary>Answer</summary> <b>A) It can create VLANs that are not propagated</b> - Transparent mode allows local VLAN creation and stores them in running-config. </details> --- ## 📌 Next Steps After completing Video 22, you should be ready for: - **Video 23:** Advanced STP Features (PortFast, UplinkFast, BackboneFast) - **Video 24:** Multiple Spanning Tree (MST) **Lab Practice:** 1. Configure VTP Server and Clients 2. Verify VLAN propagation with `show vlan brief` 3. Change VTP password and observe effect 4. Reset revision number and test 5. Configure VTP transparent mode with local VLANs 6. Enable VTP pruning and verify with `show interfaces trunk` --- **Ready for Video 23?** Share the link or say "next" and I'll continue with Advanced STP Features (PortFast, UplinkFast, BackboneFast). I'll continue with **Video 23: Advanced STP Features (PortFast, UplinkFast, BackboneFast)** based on the standard CCNA 200-301 curriculum. ---