Answer: D 

Explanation: 

NAT: Local and Global Definitions http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094837. shtml Cisco defines these terms as: Inside local address—The IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate IP address assigned by the Network Information Center (NIC) or service provider. Inside global address—A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world. Outside local address—The IP address of an outside host as it appears to the inside network. Not necessarily a legitimate address, it is allocated from an address space routable on the inside. Outside global address—The IP address assigned to a host on the outside network by the host owner. The address is allocated from a globally routable address or network space. These definitions still leave a lot to be interpreted. For this example, this document redefines these terms by first defining local address and global address. Keep in mind that the terms inside and outside are NAT definitions. Interfaces on a NAT router are defined as inside or outside with the NAT configuration commands, ip nat inside destination and ip nat outside source . Networks to which these interfaces connect can then be thought of as inside networks or outside networks, respectively. Local address—A local address is any address that appears on the inside portion of the network. Global address—A global address is any address that appears on the outside portion of the network. 

Answer: D 

Explanation: 

https://www.freeccnaworkbook.com/workbooks/ccna/configuring-inter-vlan-routing-router-on-a-stick 

Answer: B 

Explanation: 

https://learningnetwork.cisco.com/thread/12389 

I think the indication here is "Serial 0 is up, line protocol is down". What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged is not a correct answer. If you check the output of your "show interface serial 0" command again, you should notice it as "Serial 0 is down, line protocol is down. Under the "show ip int brief" you should see status = down and protocol = down as opposed to up, down. Because you disconnected the cable, layer 1 will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a cable unplugged is not a correct answer to "Serial 0 is up, line protocol is down". Up/down means that the physical layer is OK, but there is a problem with the data link link (line protocol). 

Answer: B,D,F 

Explanation: 

Switches use the destination MAC address information for forwarding traffic, while routers use the destination IP address information. Local Area Networks employ Layer 2 Switches and Bridges to forward and filter network traffic. Switches and Bridges operate at the Data Link Layer of the Open System Interconnect Model (OSI). Since Switches and Bridges operate at the Layer 2 they operate more intelligently than hubs, which work at Layer 1 (Physical Layer) of the OSI. Because the switches and bridges are able to listen to the traffic on the wire to examine the source and destination MAC address. Being able to listen to the traffic also allows the switches and bridges to compile a MAC address table to better filter and forward network traffic. To accomplish the above functions switches and bridges carry out the following tasks: MAC address learning by a switch or a bridge is accomplished by the same method. The switch or bridge listens to each device connected to each of its ports and scan the incoming frame for the source MAC address. This creates a MAC address to port map that is cataloged in the switches/bridge MAC database. Another name for the MAC address table is content addressable memory or CAM table. When a switch or bridge is listening to the network traffic, it receives each frame and compares it to the MAC address table. By checking the MAC table the switch/ bridge are able o determine which port the frame came in on. If the frame is on the MAC table the frame is filtered or transmitted on only that port. If the switch determines that the frame is not on the MAC table, the frame is forwarded out to all ports except the incoming port. 

Answer: C 

Explanation: 

Flow control is the management of data flow between computers or devices or between nodes in a network so that the data can be handled at an efficient pace. Too much data arriving before a device can handle it causes data overflow, meaning the data is either lost or must be retransmitted. For serial data transmission locally or in a network, the Xon/Xoff protocol can be used. For modem connections, either Xon/Xoff or CTS/RTS (Clear to Send/Ready to Send) commands can be used to control data flow. In a network, flow control can also be applied by refusing additional device connections until the flow of traffic has subsided. 

Reference: http://whatis.techtarget.com/definition/flow-control 

Answer: B 

Explanation: 

/30 CIDR corresponds to mask 55.255.255.252 whose binary is 11111100 which means 6 subnet bits and 2 host bits which means 62 subnets and 2 hosts per subnet. 

Answer: A,C 

Explanation: 

A primary function of a router is to forward packets toward their destination. This is accomplished by using a switching function, which is the process used by a router to accept a packet on one interface and forward it out of another interface. A key responsibility of the switching function is to encapsulate packets in the appropriate data link frame type for the outgoing data link and determining the next hop device to send the frame to. 

Answer: B,C,E 

Explanation: 

Definition of OSPF areas: An OSPF network may be structured, or subdivided, into routing areas to simplify administration and optimize traffic and resource utilization. Areas are identified by 32-bit numbers, expressed either simply in decimal, or often in octet-based dot-decimal notation, familiar from IPv4 address notation. 

See discussion following Cisco Learning discussion. 

https://learningnetwork.cisco.com/message/90832 

Answer: C 

Explanation: http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4000-series-switches/29805-175.html 

Answer: D 

Explanation: 

The first step to deploy NAT is to define NAT inside and outside interfaces. You may find it easiest to define your internal network as inside, and the external network as outside. However, the terms internal and external are subject to arbitration as well. This figure shows an example of this. 

2a.gif 

Reference: http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/13772-12.html#topic2