Download Cisco.PracticeTest.200-125.v2017-01-06.203q.vcex

Frame tagging is used when VLAN traffic travels over a trunk link. Trunk links carry frames for multiple VLANs. Therefore, frame tags are used for identification of frames from different VLANs. Inter Switch Link (ISL) and Institute of Electrical and Electronics Engineers (IEEE) 802.1q are the two frame tagging methods supported on Cisco devices. 
The purpose of frame tagging is not inter-VLAN routing. A Layer 3 device, such as a router or multilayer switch, is used for inter-VLAN routing. To configure inter-VLAN routing a logical or subinterface for each VLAN must be created on the single physical interface used to connect to the switch. An IP address is NOT applied to the physical interface; instead, each subinterface is configured with an IP address that will become the default gateway of all devices residing in that VLAN. Consequently, each subinterface and its VLAN devices must reside a different subnet as well. If a subinterface on the router is NOT configured with an IP address that resides in the same network as the hosts that reside in the VLAN that the subinterface serves, the hosts in that VLAN will be isolated from the other VLANs. The hosts in the VLAN served by the subinterface should also use this address as their default gateway, or the hosts in the VLAN will likewise be isolated form the other VLANs 
To verify the IP address of the subinterface, execute the show interfaces subinterface ID command. As shown below, the IP address will appear in line 3 of the output. Compare this IP address will the IP address set as the default gateway of each host in the VLAN served by the subinterface. They should be the same, and the IP address of the hosts should be in the same subnet as this address as well. 
router# show interfaces fastEthernet 0/0.1 
FastEthernet0/0.1 is up, line protocol is up 
Hardware is AmdFE, address is 0003.e36f.41e0 (bia 0003.e36f.41e0) 
Internet address is 10.10.10.1/24 
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 
reliability 255/255, txload 1/255, rxload 1/255 
Encapsulation ISL Virtual LAN, Color 1. 
ARP type: ARPA, ARP Timeout 04:00:00
Frame tagging does not provide encryption of network packets. Packets are transmitted unencrypted unless the network device or the application uses an additional encryption mechanism. A Virtual Private Network (VPN) is a popular solution for providing encrypted network communication. 
An access link is a connection between a switch and an end-user computer with a normal Ethernet Network Interface Card (NIC). On these links, Ethernet frames are transmitted without frame tagging. 
Objective:
LAN Switching Fundamentals 
Sub-Objective:
Configure, verify, and troubleshoot VLANs (normal/extended range) spanning multiple switches 
References:
Cisco > Cisco IOS LAN Switching Configuration Guide, Release 12.4 > Part 1: Virtual LANs > Routing Between VLANs Overview
Cisco > Technology Support > LAN Switching > Virtual LANs/VLAN Trunking Protocol (VLANs/VTP) > Design > Design Technotes > Inter-Switch Link and IEEE 802.1Q Frame Format > Document ID: 17056

The value 110 in the output represents the administrative distance (AD) of the information source. Administrative distance is used by Cisco routers to select the most trustworthy source of routing information for a particular route. Every routing protocol has a default administrative distance, and if more than one routing protocol is providing route information about a route, the protocol with the lowest AD will be selected to populate the routing table. The following table shows the AD values for different routing protocols:

  
The following is the sample output for the show ip route command:

Router# show ip route 
Gateway of last resort is 10.119.254.240 to network 10.140.0.0 
O 172.16.0.0 [110/5] via 10.19.24.6, 0:01:00, Ethernet2
B 172.17.12.0 [200/128] via 10.19.24.24, 0:02:22, Ethernet2
O 172.71.13.0 [110/5] via 10.19.24.6, 0:00:59, Ethernet2
O 10.13.0.0 [110/5] via 10.19.24.6, 0:00:59, Ethernet2

The following are the fields in the output:
O: Indicates that the route was discovered using Open Shortest Path First (OSPF).
B: Indicates that the route was discovered using Border Gateway Protocol (BGP).
172.16.0.0: Indicates the address of the remote network.
110: Indicates the administrative distance of the route.
128: Indicates the metric for the route.
Via 10.19.24.6: Specifies the address of the next router in the remote network.
0:02:22: Indicates the last time the route was updated.
The metric for the route is also called the cost. In the case of the OSPF routes above, the cost is 5. 
The administrative distance for any particular protocol can be changed if you would like to use a routing protocol that is normally not the preferred provider. For example, if you prefer that RIP routes be installed in the routing table rather than OSPF routes, you could change the administrative distance of RIP to a lower value than OSPF (110), as shown below. 

Router(config)# router rip 
Router(config)# distance 100 

All the other options are incorrect because they do not represent the administrative distance. 

Objective:
Routing Fundamentals 
Sub-Objective:
Interpret the components of routing table 

References:
Cisco > Support > IP > IP Routing > Design > Design TechNotes > What Is Administrative Distance? > Document ID: 15986

The following commands are used on Cisco routers to set a password for Telnet lines:
router(config)# line vty 0 4 
router(config-line)# login 
router(config-line)# password password 
An explanation of the commands is below:
router(config)# line vty 0 4: Enters line configuration mode for virtual terminal lines 0 to 4.
router(config-line)# login: Ensures that any remote access is prompted for a password.
router(config-line)# password password: Sets a password of "password" for VTY lines.
Assigning a password to the VTY lines is required for remote connections to the device to be possible. If a password has not been configured the following error message will be generated when the connection is attempted:
Password required but not set 
[Connection to foreign host 106.5.5.1 closed by foreign host] 
Configuring a VTY password and requiring the password (accomplished with the login command) is good first step in securing Telnet access to the device. Another step that can enhance the security of remote access to the device would be to apply an access list to the VTY lines with the access-class command. 
The command sequence which begins with router(config-router)# line vty 0 4 is incorrect because the line vty 0 4 command should be executed in global configuration mode, not routing protocol configuration mode. 
The line telnet 0 4 command is incorrect because this is not a valid Cisco IOS command. 
The line aux 0 command is incorrect because this allows you to configure the properties of the Auxiliary port, as opposed to the incoming Telnet (VTY) lines. 
Objective:
Infrastructure Management 
Sub-Objective:
Configure and verify device management 
References:
Cisco > Support > Technology Support > IP > IP Addressing Services > Design > Design TechNotes > Cisco Guide to Harden Cisco IOS Devices > Document ID: 13608
Cisco > Support > End-of-sale and End-of-life Products > Cisco IOS Software Releases 11.0 > Configuration Examples and TechNotes > Telnet, Console and AUX Port Passwords on Cisco Routers Configuration Example

When a class C address such as 192.168.54.0 is subnetted with a /27 mask, the subnet mask in dotted decimal format is 255.255.255.224. This means that the interval between the network IDs of the resulting subnets is 32. The resulting network IDs are as follows:
192.168.54.0 
192.168.54.32 
192.168.54.64 
192.168.54.92 and so on. 
Therefore, the address 192.168.54.23 resides in the 192.168.54.0 subnet. The address 192.168.54.0 is called a network ID or, alternately, a subnet address. It represents the subnet as a group and will be used in the routing tables to represent and locate the subnet. 
Neither the first address (192.168.54.0, the network ID) nor the last address (192.168.54.31, the broadcast address) in any resulting subnet can be used. Therefore, the addresses in this range are 192.168.54.1 through 192.168.54.30, which includes the 192.168.54.23 address. 
192.168.54.8 would only be a network ID if the mask were /29, which would result in an interval of 8 between network IDs. However, even if a /29 mask were used, the 192.168.54.23 address would not fall in its range. The address range for a /29 mask would be 192.168.54.9 through 192.168.54.14. 
Similarly, 192.168.54.4 would only be a network ID for a /30 mask, which would result in an interval of 4 between network IDs. But even if a /30 mask were used, the 192.168.54.23 address would not fall in its range. The address range for a /30 mask would be 192.168.54.5 through 192.168.54.6. 
192.168.54.16 could be a network ID if the mask were /28, /29 or /30, but not with a /27 mask. 
Objective:
Network Fundamentals 
Sub-Objective:
Apply troubleshooting methodologies to resolve problems 
References:
Cisco > Support > IP Routing > Design TechNotes > Document ID: 13788 > IP Addressing and Subnetting for New Users

VTP manages configured VLANs across a switched network and maintains consistency of VLAN information throughout a VTP domain. When an administrator adds, deletes, or renames VLANs, VTP propagates this information to all other switches in the VTP domain. This makes the process of VLAN changes a plug-and-play activity. This protocol was developed by, and remains proprietary to Cisco Systems. 
Broadcast control is not the primary benefit of VTP. Broadcast control is achieved by using VLANs. VLANs segment the network into logical broadcast domains. This helps in the reduction of unnecessary traffic over the network and optimizes the available bandwidth use. VTP pruning helps reduce broadcast and unknown unicast over VLAN trunk links. However, this is not the primary benefit of VTP. 
Frame tagging is required for VLAN identification as frames traverse trunk links in a switch fabric. Inter-Switch Link (ISL) and IEEE 802.1q are the two methods of frame tagging available on Cisco devices. ISL is proprietary to Cisco, whereas IEEE 802.1q is a standard method. VTP is not a frame tagging method. 
Inter-VLAN routing is achieved by an Open Systems Interconnect (OSI) Layer 3 device (Router). Inter-VLAN routing is not a benefit of VTP. 
Objective:
LAN Switching Fundamentals 
Sub-Objective:
Configure, verify, and troubleshoot VLANs (normal/extended range) spanning multiple switches 
References:
Cisco > Support > LAN Switching > Virtual LANS / VLAN Trunking Protocol (VLANS/VTP) > Configure > Configuration Examples and Technotes > Configuring VLAN Trunk Protocol (VTP) > Document ID: 98154
Cisco > Catalyst 4500 Series Switch Cisco IOS Software Configuration Guide, 12.2(25) > Understanding and Configuring VLANs, VTP, and VMPS