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200 Cards in this Set
- Front
- Back
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What is a network?
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A collection of systems and devices exchanging data over some form of media.
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What is a host?
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A device that holds a logical address on the network.
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What is a protocol?
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An agreed upon set of rules for a particular network function.
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What is bandwidth?
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The total amount of data (in bits) you can theoretically transmit within a given time period (typically one second).
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What is throughput?
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The actual measurement of the data that's able to pass through the media at any given time.
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What is the difference between simplex and duplex transmission?
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Devices can only send in one direction.
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What does the physical topology refer to in networking?
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How the network actually looks from a bird's-eye view. The physical cabling layout of the network itself.
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What are the five different physical topologies?
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1. Bus
2. Ring 3. Star 4. Mesh 5. Hybrid |
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What is the formula for calculating the number of links in a mesh network?
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N(N-1)/2, where N is the number of hosts.
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What are hybrid topologies?
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Any combination of two or more physical topologies.
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What is a LAN?
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A network that serves users within a small geographic footprint.
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What is a WAN?
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A network connecting a collection of LANs across a wide geographic area—perhaps a state, nation, or even the whole world!
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What is the most common LAN technology?
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Ethernet.
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What are the three major categories of WAN technologies?
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1. Circuit switched
2. Packet (or cell) switched 3. Dedicated connections (point to point) |
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How do circuit switched connections work?
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Like your telephone at home. When you wish to transmit, you make a call and the line is in use until you are finished transmitting.
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What WAN technologies use circuit switching?
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Regular dial-up with a modem, using POTS or Integrated Services Digital Networking (ISDN).
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What are the advantages of circuit switched technologies?
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Cost (cheaper, generally), scalability (easy to install and expand), and availability.
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How do packet or cell switched connections work?
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The point-to-point circuits between devices are opened for the length of time it takes to send a message, and are then cleared for use.
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What is the difference between cell switching and packet switching networks?
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The length of the individual packet sent.
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What is the advantage of packet/cell switching technologies?
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Packet switching allows multiple connections from one device.
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How do point-to-point/dedicated WAN connections work?
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A leased line directly connects one network to another.
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What are the advantages of direct connections?
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The connection is always up and available, and you are guaranteed 100 percent of the bandwidth available 100 percent of the time.
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What is a small office/home office (SOHO)?
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Refers to a single user, or a small group of people (one to ten), working from a single location, such as a home or office space.
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What is a branch office?
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Supports a small group of people, just as the SOHO does. However, it has its own LAN and is considered a part of the overall corporation or enterprise.
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What is a mobile user?
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Forms part of the corporation, but is not located at a branch office.
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What is the main purpose of the OSI Reference Model?
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To provide a means for us to break down the communications process between two computers into stages, and easily discuss and describe the steps within each stage.
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What is encapsulation?
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The process of adding a header and a trailer to a piece of data.
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What benefits does the OSI Reference Model provide?
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"It simplifies training and learning.
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What are the disadvantages of direct connections?
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Whether you use the bandwidth or not, you pay for it and generally speaking, these connections are rather expensive to implement.
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What are the disadvantages of packet/cell switching technologies?
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Generally much more expensive than circuit switching and are also harder to implement and may not be available in all locations.
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Which OSI layer is concerned with reliable end-to-end delivery of data?
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Transport layer
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At what layer of the OSI model would you find framing?
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Data Link layer
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What is the PDU at layer 4 called?
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Segment
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What is the PDU at layer 3 called?
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Packet
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The Transport layer on the recipient machine requests a retransmission of a segment from the sending machine. This is an example of:
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Same layer interaction
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In which layer of the TCP/IP stack is routing and logical addressing found?
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Internet layer
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In which layer of the TCP/IP stack is framing found?
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Network Access layer
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Which TCP/IP Application layer protocol provides IP address resolution for domain names?
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DNS
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TCP completes a three-way handshake before exchanging data. In order, what are the steps?
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SYN, SYN/ACK, ACK
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What is the well-known port number for SMTP?
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25
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This point-to-point protocol was replaced by PPP, largely because it could only transport TCP/IP.
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SLIP
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Which cable type would be used to connect a router to a switch?
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Straight-through
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Which network device monitors network traffic for network attack signatures and notifies administrators when an attack is in progress?
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An IDS
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Which network device monitors network traffic for network attack signatures and is capable of stopping the attack in progress?
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An IPS
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Pin 1 on the PC NIC is set to?
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Transmit.
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Hub port pinouts have pins 1 and 2 set to?
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Receive.
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Hub port pinouts have pins 3 and 6 set to?
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Transmit.
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What is the name of the Frame Relay field used to identify Frame Relay virtual circuits?
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Data-link connection identifier.
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A leased line is installed between each router and a nearby Frame Relay switch; these links are called?
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Access links.
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What functions as the DCE in Frame Relay?
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The Frame Relay switches
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What functions as a DTE in Frame Relay?
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The customer equipment (router).
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In Frame Relay, the logical path that a frame travels between each pair of routers is called?
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A Frame Relay VC.
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What is the committed information rate (CIR)?
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The minimum bandwidth guaranteed by the provider.
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Each Class B network contains how many IP addresses that can be assigned to hosts?
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65,534
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Each Class C network contains how many IP addresses that can be assigned to hosts?
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254
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What is a routing protocol?
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A protocol that aids routers by dynamically learning about the groups of addresses in the network.
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A value used to prevent routing loops.
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TTL.
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What learns routes and puts those routes in a routing table?
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Routing protocols.
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What are the two key points about how IP addresses are organized?
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* All IP addresses in the same group must not be separated by a router.
* IP addresses separated by a router must be in different groups. |
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What are the two reserved IP addresses for every network?
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* The network address (all zeros)
* The broadcast address (all ones) |
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What is the size of a DS0?
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64 kbps
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What is the size of a DS1 (T1)?
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1.544 Mbps (24 DS0s, plus 8 kbps overhead)
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What is the size of a E1?
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2.048 Mbps (32 DS0s)
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What does Cisco HDLC frames have that is not found in the standard HDLC frames?
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A type field.
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The process of forwarding packets (Layer 3 PDUs).
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Routing
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Addresses that can be used regardless of the type of physical networks used, providing each device (at least) one address. Enables the routing process to identify a packet's source and destination.
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Logical addressing
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A protocol that aids routers by dynamically learning about the groups of addresses in the network, which in turn allows the routing (forwarding) process to work well.
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Routing protocol
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The primary tool for testing basic network connectivity.
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Ping
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What are the two steps used by hosts when routing packets?
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Step 1 - If the destination IP address is in the same subnet as I am, send the packet directly to that destination host.
Step 2 - If the destination IP address is not in the same subnet as I am, send the packet to my default gateway. |
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What is the default duplex status for a Cisco switch?
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Auto
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Describe the Layer 4 feature called error recovery (reliability)?
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The process of numbering and acknowledging data with Sequence and Acknowledgment header fields.
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A protocol that requires an exchange of messages before data transfer begins or that has a required preestablished correlation between two endpoints
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Connection-oriented protocol
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A protocol that does not require an exchange of messages and that does not require a preestablished correlation between two endpoints
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Connectionless protocol
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The size of the largest Layer 3 packet that can sit inside a frame's data field.
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maximum transmission unit (MTU)
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Ethernet MTU
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1500 bytes.
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An attack whose purpose is to break things.
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Denial of service (DoS) attacks
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A program that is somehow transferred onto an unsuspecting computer, possibly through an e-mail attachment or website download. This program could just cause problems on the computer, or it could steal information and send it back to the attacker.
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Computer viruses
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Can monitor when devices first connect to a LAN, be they wireless or wired and can prevent a computer from connecting to the LAN until its virus definitions were updated. It also includes a requirement that the user supply a username and password before being able to send other data into the LAN.
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Network Admission Control (NAC)
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A virus that looks for private or sensitive information, tracking what the user does with the computer, and passing the information back to the attacker in the Internet.
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Spyware
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A self-propagating program that can quickly replicate itself around Enterprise networks and the Internet, often performing DoS attacks, particularly on servers.
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Worm
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A virus that logs all keystrokes, or possibly just keystrokes from when secure sites are accessed, reporting the information to the attacker.
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Keystroke logger
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The attacker sets up a website that outwardly looks like a legitimate website, often for a bank or credit card company, but is an illegitimate website designed to capture private information.
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Phishing
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This refers to a broad class of malicious viruses, including spyware.
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Malware
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Refers to the whole class of security tools that prevent various problems, including Anti-virus, Anti-spyware, Anti-spam, Anti-phishing, URL filtering, and E-mail filtering tools.
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Anti-x
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A security tool that typically receives a copy of packets via a monitoring port, rather than being part of the packets' forwarding path. This tool can then rate and report on each potential threat, and potentially ask other devices, such as firewalls and routers, to help prevent the attack (if they can).
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Intrusion Detection Systems (IDS)
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This security tool often sits in the packets' forwarding path, giving it the capability to perform the same functions as the IDS, but also to react and filter the traffic.
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Intrusion Prevention Systems (IPS)
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A frame sent with a destination address of FFFF.FFFF.FFFF and implies that all devices on the LAN should receive and process the frame.
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Broadcast addresses
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Addresses used to allow a dynamic subset of devices on a LAN to communicate. The MAC addresses used in the Ethernet frame follow this format: 0100.5exx.xxxx.
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Multicast addresses
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Content Addressable Memory (CAM)
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The type of physical memory used to store the MAC address table.
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The switch fully receives all bits in the frame before forwarding the frame. This allows the switch to check the FCS before forwarding the frame.
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Store-and-forward switching method
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The switch forwards the frame as soon as it can. This reduces latency but does not allow the switch to discard frames that fail the FCS check.
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Cut-through switching method
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The switch forwards the frame after receiving the first 64 bytes of the frame, thereby avoiding forwarding frames that were errored due to a collision.
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Fragment-free switching method
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What does a LAN consist of?
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All devices in the same broadcast domain.
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List five motivations/benefits of using VLANs.
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1. To create more flexible designs that group users by department, or by groups that work together, instead of by physical location.
2. To segment devices into smaller LANs (broadcast domains) to reduce overhead caused to each host in the VLAN. 3. To reduce the workload for STP by limiting a VLAN to a single access switch. 4. To enforce better security by keeping hosts that work with sensitive data on a separate VLAN. 5. To separate traffic sent by an IP phone from traffic sent by PCs connected to the phones. |
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Cisco uses three terms to describe the role of each switch in a campus design. What are they?
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1. Core
2. Distribution 3. Access |
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Describe Access switches
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Switches that connect directly to end users, providing access to the LAN.
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Describe Distribution switches
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Switches that provide a path through which the access switches can forward traffic to each other.
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Describe Core switches
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Aggregates distribution switches in very large campus LANs, providing very high forwarding rates.
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The default console port settings on a switch are?
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* 9600 bits/second
* No hardware flow control * 8-bit ASCII * No stop bits * 1 parity bit |
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The four main types of memory found in Cisco switches are?
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1. RAM
2. ROM 3. NVRAM 4. Flash |
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What is stored in the RAM of Cisco routers and switches?
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The running (active) configuration file is stored here.
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What is stored in the ROM of Cisco routers and switches?
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Stores a bootstrap (or boothelper) program that is loaded when the switch first powers on. This bootstrap program then finds the full Cisco IOS image and manages the process of loading Cisco IOS into RAM, at which point Cisco IOS takes over operation of the switch.
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What is stored in the Flash memory of Cisco devices?
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It stores fully functional Cisco IOS images and is the default location where the switch gets its Cisco IOS at boot time.
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What is stored in the NVRAM of Cisco devices?
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Stores the initial or startup configuration file that is used when the switch is first powered on and when the switch is reloaded.
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Configure SSH on Cisco switch:
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>enable
#configure terminal (config)#line vty 0 4 (config-line)#login local (config-line)#transport input ssh (config-line)#exit (config)#username John password Doe (config)#ip domain-name imlost.com (config)#crypto key generate rsa (config)#end |
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What are the three banners available on Cisco switches?
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MOTD, login, and exec.
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This message is shown before the login prompt. For temporary messages that may change from time to time.
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Message of the Day (MOTD) banner
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Shown before the login prompt but after the MOTD banner. For permanent messages such as "Unauthorized Access Prohibited."
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Login banner
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Shown after the login prompt. Used to supply information that should be hidden from unauthorized users.
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Exec banner
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Configure MOTD banner
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>enable
#configure terminal (config)#banner motd # Switch down for maintenance at 11PM Today # (config)#exit # |
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Configure login banner
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>enable
#configure terminal (config)#banner login # Unauthorized Access Prohibited!!!! # (config)#exit # |
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Configure exec banner
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>enable
#configure terminal (config)#banner exec Z Company picnic at the park on Saturday. Don't tell outsiders! Z (config)#exit # |
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How do you configure a static IP address on a Cisco switch?
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switch1#configure terminal
switch1(config)#interface vlan 1 switch1(config-if)#ip address 192.168.1.200 255.255.255.0 switch1(config-if)#no shutdown switch1(config-if)#exit switch1(config)#ip default-gateway 192.168.1.1 switch1(config)#exit switch1# |
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On a Cisco switch, what does interface status "err-disabled" indicate?
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Port security has disabled the interface.
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On a Cisco switch, what does interface status "disabled" indicate?
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The interface is configured with the shutdown command.
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What is a late collision?
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When a switch has already sent 64 bytes of a frame, and the switch receives another frame on that same interface.
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If the CRC errors grow, but the collisions counters do not, the problem may simply be what?
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Interference on the cable.
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An incrementing late collisions counter typically means one of two things:
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* The interface is connected to a collision domain whose cabling exceeds Ethernet cable length standards.
* The interface is using half duplex, and the device on the other end of the cable is using full duplex. |
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What counter values indicate excessive noise?
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Many input errors, few collisions
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What is the common root cause of excessive noise?
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Wrong cable category (Cat 5, 5E, 6); damaged cables; EMI
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What counter values indicate excessive collisions?
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More than roughly .1% of all frames are collisions
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What is the common root cause of excessive collisions?
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Duplex mismatch (seen on the half-duplex side); jabber; DoS attack
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What counter values indicate excessive late collisions?
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Increasing late collisions values.
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Down Down notconnect"
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No cable; bad cable; wrong cable pinouts; the speeds are mismatched on the two connected devices; the device on the other end of the cable is powered off or the other interface is shutdown.
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cdp run
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Global command that enables CDP for the entire switch or router.
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cdp enable
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Interface subcommand that enables CDP for a particular interface.
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What are the differences with the router CLI as compared to the switch CLI?
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* The configuration of IP addresses differs in some ways.
* The questions asked in setup mode differ. * Routers have an auxiliary (Aux) port, intended to be connected to an external modem to allow remote users to access the CLI. |
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The clock rate command
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dictates the actual speed used to transmit bits on a serial link.
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If you do not know which router has the DCE cable in it, how can you find out?
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By using the show controllers command.
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What routing protocols use the interface bandwidth settings to set their default metrics, with the metrics impacting a router's choice of the best IP route to reach each subnet?
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The EIGRP and OSPF routing protocols.
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Every router interface has a default setting of the bandwidth command that is used when there is no bandwidth command configured on the interface. What is it?
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* For serial links, the default bandwidth is 1544.
* Ethernet interfaces default to a bandwidth setting that reflects the current speed of the interface. |
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Do Cisco switches have an Aux port?
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No.
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List the process to upgrade an IOS image into Flash memory:
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Step 1 - Obtain IOS image from Cisco, by downloading the IOS image from Cisco.com using HTTP or FTP.
Step 2 - Place IOS image into the default directory of a TFTP server that is accessible from the router. Step 3 - Issue the copy command from the router, copying the file into Flash memory. --> R1#copy tftp flash |
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During the process of copying the IOS image into Flash memory, the router will ask what questions?
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1. What is IP address or host name of the TFTP server?
2. What is name of the file? 3. Is space available for this file in Flash memory? 4. Does the server actually have a file by that name? 5. Do you want the router to erase the old files? |
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Which command shows the current value of the configuration register?
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The show version command.
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To enter the ROM monitor set the configuration register value to?
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0x2100
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To configure the system to use the boot system commands in NVRAM, set the configuration register to?
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Any value from 0x2102 to 0x210F.
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To install a router, follow these steps:
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Step 1 - Connect any LAN cables to the LAN ports.
Step 2 - If using an external CSU/DSU, connect the router's serial interface to the CSU/DSU, and the CSU/DSU to the line from the telco. Step 3 - If using an internal CSU/DSU, connect the router's serial interface to the line from the telco. Step 4 - Connect the router's console port to a PC (using a rollover cable), as needed, to configure the router. Step 5 - Connect the power cable. Step 6 - Turn on the router. |
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What conditions must be met for a router to add routes to its routing table for the subnets connected to each of the router's interfaces?
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First, router must have IP address and mask configured on the interface.
Second, both interface status codes must be "up." |
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(T or F) To add a static route to the IP routing table, the next-hop router IP address must be in an "up and up" state.
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True.
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The ip route command allows a slightly different syntax on point-to-point serial links. What is it?
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You can configure the outgoing interface instead of the next-hop IP address.
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What is the primary goal of IP routing protocols?
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To fill the IP routing table with the current best routes it can find.
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RIP routers send periodic routing updates about every ____ seconds by default.
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30
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IP routing protocols fall into one of two major categories:
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* Interior Gateway Protocol (IGP)
* Exterior Gateway Protocol (EGP) |
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Define Interior Gateway Protocol (IGP):
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A routing protocol that was designed and intended for use inside a single autonomous system.
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Define Exterior Gateway Protocol (EGP):
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A routing protocol that was designed and intended for use between different autonomous systems.
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What is an autonomous system?
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An internetwork under the administrative control of a single organization.
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Only one routing protocol is used today to exchange routes between routers in different autonomous systems.
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Border Gateway Protocol (BGP)
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(T or F) By assigning each autonomous organization an ASN, BGP can ensure that packets do not loop around the global Internet by making sure that packets do not pass through the same autonomous system twice.
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TRUE
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RIP uses a metric called what?
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Hop count.
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How is the EIGRP metric calculated?
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It considers both the interface bandwidth and interface delay settings as input into a mathematical formula to calculate the metric.
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What are the steps to configure RIP?
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Step 1 - Use the router rip configuration command to move into RIP configuration mode.
Step 2 - Use the version 2 RIP subcommand to tell the router to use RIP Version 2 exclusively. Step 3 - Use one or more network net-number RIP subcommands to enable RIP on the correct interfaces. Step 4 - (O) As needed, disable RIP on an interface using the passive-interface type number RIP subcommand. |
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What is the multicast IP address for RIP-2 updates?
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224.0.0.9
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This command lists one line per router interface, including the IP address and interface status.
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show ip interface brief
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This command lists the routing table, including RIP-learned routes, and optionally just RIP-learned routes.
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show ip route [rip]
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This command lists information about the RIP configuration, plus the IP addresses of neighboring RIP routers from which the local router has learned routes.
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show ip protocols
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What is the Administrative Distance (AD)?
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A numeric value assigned to each routing protocol and used to select the best route (lower number).
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What is the Administrative Distance of EIGRP?
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90
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What is the Administrative Distance of RIP?
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120
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What is the Administrative Distance of OSPF?
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110
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What is the Administrative Distance of connected routes?
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0
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What is the Administrative Distance of static routes?
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1
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RIP-1 sends updates to what address?
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The 255.255.255.255 broadcast address.
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The three things that occur on an interface matched by a RIP-2 network command.
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1. The router multicasts routing updates to 224.0.0.9.
2. The router listens for incoming updates on that same interface. 3. The router advertises about the subnet connected to the interface. |
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Global command that tells the router to put a timestamp on log messages, including debug messages.
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service timestamps
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Global command that defines a static route.
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ip route network mask {ip-addr | interface type/number}
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RIP subcommand that tells RIP to no longer advertise RIP updates on the listed interface.
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passive-interface [default] { interface type/number}
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This command lists info about the various processes running in IOS, and most importantly, overall CPU utilization statistics.
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show process
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For the length of the user's session, this command causes IOS to display mask info in dotted-decimal format instead of prefix format.
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terminal ip netmask-format decimal
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The term Public Switched Telephone Network (PSTN) refers to:
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The equipment and devices that telcos use to create basic telephone service between any two phones in the world.
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The original standard for converting analog voice to a digital signal is called?
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Pulse-code modulation (PCM).
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What are some of the key features of DSL?
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* Allows analog voice signals and digital data signals to be sent over the same local loop wiring at the same time.
* The local loop must be connected to something besides a traditional voice switch at the local CO, in this case a device called a DSL access multiplexer (DSLAM). * Allows for a concurrent voice call to be up at the same time as the data connection. * Unlike modems, DSL's data component is always on; in other words, you do not have to signal or dial a phone number to set up a data circuit. |
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The speed of DSL can vary widely, based on what factors?
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* The distance between the CO and the consumer
* The quality of the local loop cabling * The type of DSL (each standard has different maximum theoretical speeds) * The DSLAM used in the CO (older equipment may not have recent improvements that allow for faster speeds on lower-grade local loops) |
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What is the length of ATM cells?
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53 bytes in length
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To support the web browser, a router must first be configured from the CLI with what?
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At least one IP address, typically on the local LAN, so that the engineer's computer can connect to the router.
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You can configure the DHCP client, DHCP server, and PAT functions with SDM using the following five major steps:
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Step 1 - Establish IP connectivity. (from the CLI)
Step 2 - Install and access SDM. Step 3 - Configure DHCP and PAT. Step 4 - Plan for DHCP services. Step 5 - Configure the DHCP server. |
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To configure the DHCP server with SDM:
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1. Click Configure near the top of the SDM window.
2. Click Additional Tasks at the bottom of the Tasks pane to open the Additional Tasks window. 3. Select the DHCP Pools option on the left. 4. Click Add button to open the Add DHCP Pool dialog box. |
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What should you do when some users' connections that need to use NAT work fine, and other users' connection that need to use NAT do not work at all?
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Run the "clear ip nat translation * " command.
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This command lists info learned from a DHCP server, by a router acting as a DHCP client.
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show dhcp server
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The process by which a TCP/IP host sends data can be viewed as a five-step process.
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Step 1 - Create and encapsulate the application data with any required application layer headers.
Step 2 - Encapsulate the data supplied by the application layer inside a transport layer header. Step 3 - Encapsulate the data supplied by the transport layer inside an internet layer (IP) header. Step 4 - Encapsulate the data supplied by the internet layer inside a network access layer header and trailer. Step 5 - Transmit the bits. |
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The CSMA/CD algorithm works like this:
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Step 1 - A device with a frame to send listens until the Ethernet is not busy.
Step 2 - When the Ethernet is not busy, the sender(s) begin(s) sending the frame. Step 3 - The sender(s) listen(s) to make sure that no collision occurred. Step 4 - If a collision occurs, the devices that had been sending a frame each send a jamming signal to ensure that all stations recognize the collision. Step 5 - After the jamming is complete, each sender randomizes a timer and waits that long before trying to resend the collided frame. Step 6 - When each random timer expires, the process starts over with Step 1. |
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A router uses the following logic when receiving a data-link frame—a frame that has an IP packet encapsulated in it:
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Step 1 - Use the data-link FCS field to ensure that the frame had no errors; if errors occurred, discard the frame.
Step 2 - Assuming the frame was not discarded at step 1, discard the old data-link header and trailer, leaving the IP packet. Step 3 - Compare the IP packet's destination IP address to the routing table, and find the route that matches the destination address. This route identifies the outgoing interface of the router, and possibly the next-hop router. Step 4 - Encapsulate the IP packet inside a new data-link header and trailer, appropriate for the outgoing interface, and forward the frame. |
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The following steps list the commands used to configure IP on a switch:
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Step 1 - Enter VLAN 1 configuration mode using the interface vlan 1 global configuration command.
Step 2 - Assign an IP address and mask using the ip address ip-address mask interface subcommand. Step 3 - Enable the VLAN 1 interface using the no shutdown interface subcommand. Step 4 - Enter the ip default-gateway ip-address global command to configure the default gateway. |
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To install a router, follow these steps:
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Step 1 - Connect any LAN cables to the LAN ports.
Step 2 - If using an external CSU/DSU, connect the router's serial interface to the CSU/DSU, and the CSU/DSU to the line from the telco. Step 3 - If using an internal CSU/DSU, connect the router's serial interface to the line from the telco. Step 4 - Connect the router's console port to a PC (using a rollover cable), as needed, to configure the router. Step 5 - Connect a power cable from a power outlet to the power port on the router. Step 6 - Turn on the router. |
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List steps in the routing process:
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Step 1 - Router checks the frame's FCS for errors.
Step 2 - Router then discards the Ethernet header and trailer. Step 3 - Router compares the packet's destination address to the routing table and finds the entry for subnet. Step 4 - Router forwards the packet to next-hop router after encapsulating the packet in a HDLC frame. |
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A DS1, also called a T1 line has what characteristics?
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A single line that supports 24 DS0s, plus an 8-kbps overhead channel, for a speed of 1.544 Mbps.
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What is an E1 line?
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A standard used in Europe and Japan holds 32 DS0s.
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How many DS0s make a T1 line?
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24 DS0s.
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How many DS0s make an E1 line?
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32 DS0s.
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How many DS1s make a DS3 line?
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28 DS1s.
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How many E1s make an E3 line?
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16 E1s.
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You see the names of the routers you traverse when using the Windows Tracert command, but not when using the router's traceroute command. How can you fix this?
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Configure DNS via ip name-server ip address command.
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When would a switch revert to store and forward mode?
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When a port is already busy transmitting or receiving and another station sends a frame to that busy port, the switch will store the new frame until the port is available.
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When a frame is too big to fit on an intermediate LAN, what happens?
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The network layer fragments it.
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How can you tell if your router booted into RxBoot mode?
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The prompt will be Router(boot)>.
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What does WEP stand for?
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Wired Equivalent Privacy.
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Routers' routing tables have three kinds of entries. What are they?
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Connected, static, and routed.
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What are the two trunking protocols supported by Cisco switches?
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802.1q and ISL.
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What is the command to display the current value of the configuration register?
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show version
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What Cisco command clears all the NAT mappings in the NAT table?
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The clear ip nat translation * command clears all the NAT translations in the NAT table. This command is useful for troubleshooting NAT.
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