VLANs and VTP
Virtual Local Area Network or VLANs are a way to segment traffic in a network. These VLANs are built on the concept of trunking which on a Cisco switch allow traffic from multiple VLANs to access that link. The trunk is essentially for two or more VLANs that can go across it. VTP is Virtual Trunking Protocol and is a Cisco proprietary protocol that can help manage the VLANs on multiple networking devices. Understanding VLANs and VTP is something that would help you study for and pass the CCNA exam.
Trunking
Trunking is something on a Cisco switch that allows for tagging VLANs that are able to access the trunk link. If set up correctly with the 802.1q encapsulation you can manage the trunk links by tagging these trunks and keeping the untagged ports as access ports. There are some additional settings like allowed VLANs on a trunk link. A trunk link must have the 802.1q encapsulation on both sides of the link in order to operate as a trunk. There is a Cisco encapsulation that is an older way to configure trunks which is ISL or Inter-Switch Link.
VLANs and VLAN Pruning
VLANs have some settings that you can configure like allowing a Voice VLAN, an access VLAN and the native VLAN, that is the default option for VLANs. VLAN pruning is something that is more for disabling a certain VLAN on a switch so that the VLANs don’t require extra work on a switch that doesn’t need it. The VLAN pruning option is configured for the switches that don’t use all of the allowed VLANs on a trunk.
VTP Modes and Domains
VTP has three modes which are Transparent, Client, and Server. These modes replicate changes to the VLAN database with Client only receiving the updates, Server managing the updates and Transparent that doesn’t allow anything but local updates. There are some configuration items for VTP like configuring a VTP Domain, and a VTP Password. Additionally, the revision number is the thing that switches look at to see if they have the newest VTP changes.
Conclusion
VLAN and VTP configurations do matter on the network as this is how the VLAN database changes are configured on a LAN. There are additional configuration options that are available and note that you need to configure an access port with switchport mode access and switchport access VLAN 10 or whatever the VLAN is for it to work. In order to configure a trunk on a Cisco switch you will need to set the encapsulation on both sides and then configure the switchport mode trunk to get both sides to enable the trunk.