Glossary of Cisco CCNA Routing Fundamentals
Other Decks By This User
- What 3 things are loaded when the router is initialized?
- 1. Bootstrap
2. The Operating System
3. Configuration File
- What does a router do if it cannot find a configuration file?
- Enters setup mode
- Where is the backup copy of the new configuration from setup mode stored?
- What is the test called that the router performs when it powers up?
- After verifying Hardware functions what does the router do next?
- Software initialization
- Where is the bootstrap program loaded
- What is the definition of Bootstrap
- A bootstrap is a simple preset operation to load instructions that in turn cause other instructions to be loaded into memory, or cause entry into other configuration modes
- Where are three places where the Cisco IOS can be found?
- 1. Flash
2. TFTP Server
- Where is the configuration file saved?
- What 3 things does the POST Diagnostics from ROM verify.
- 1. Basic CPU operation
3. Network Interface ports
- How are configuration files loaded into main memory?
- one line at a time
- what do configuration commands do?
- 1. Start routing
2. Supply addresses for interfaces
3. set media charachteristics and so on
- If no valid configuration file exists in NVRAM, the OS executes a question driven configuration routine. What is this called
- System configuration Dialog or setup Dialog
- What command shows the backup config files
- Show startup-config
- What command shows the active config files
- Show running-config
- What command deletes the backup configuration file in NVRAM
- Erase startup-config
- What is the reboot command
- What is the command used to enter setup mode from the privledged exec prompt
- What is the purpose of setup mode?
- to bring up, quickly, a minimal configuration for any router that cannot find its configuration from some other source
- How do default answers appear in setup mode
- in brackets 
- what command can be pressed at any time to terminate the process and start over
- Control + C
- If you want to use the new configuration and you enter yes where will it be saved
- What should you do if the MORE promp appears
- press space bar to continue
- What is the first global parameter you should enter?
- Host name
- What password is encrypted by Cisco proprietary software?
- Enable Secret
- How does the enable secret password appear on the config file?
- meaningless string of charachters
- If you answer yes to the setup configuration what will happen to the configuration file?
- it will be executed and saved to NVRAM
- if you want to change the setup configuration after you save it what must be done.
- You must configure it manually
- The script file generated by setup is additive. What does this mean?
- You can turn features on with setup but you can not turn them off.
- What 3 places can you load configuration files from?
- 1. Console
3. TFTP server
- What five pieces of information does the router use from the configuration files when it starts up?
- 1. Cisco IOS Software version
2. Router Identification
3. Boot File Locations
4. Protocol Information
5. Interface Configuration
- If there is no configuration file in the router, what mode do you enter to configure one?
- What command will allow you to configure from a virtual terminal, a modem, or a console terminal?
- privledged EXEC configure
- What command configures manually from the console terminal.
- configure terminal
- What command displays the current configuration in RAM?
- Show running-config
- What command displays the saved configuration, which is the contents of NVRAM?
- show startup-config
- What command erases the contents of NVRAM?
- erase startup-config
- What does the command copy running-config tftp allow you to do?
- store a current copy of the configuration on a TFTP server.
- In copying a running-config to a host do you need to key the IP address of the host?
- Do you need to name a config file copied to a TFTP server?
- What mode do you need to be in, in order to manage the contents of NVRAM
- What command erases the contents of NVRAM
- erase startup-config
- Where is the runnning config stored?
- Where is the startup or backup configuration file stored?
- What command stores the current configuration into NVRAM?
- copy running-config startup-config
- What command displays the saved configuration?
- show startup-config
- If the screen prompt shows
Router(config-if)# what are you configuring?
- the interface
- If the screen prompt shows Router(config-subif)# what are you configuring?
- the subinterface
- What mode are you in when you apply commands that affect the system as a whole?
- Global configuration
- What do you type to enter global configuration mode from the terminal
- Configure Terminal or
- What command do you key to configure a routing protocol?
- Router "protocol" for example to configure RIP you type
- What mode are all router interfaces automatically in?
- administratively down mode
- What is the clocking signal on a serial link?
- What tyoe of devices are, by default, cisco routers?
- what command sets the clockrate?
- What command establishes a password on the console terminal?
- line console 0
line con 0
- What command establishes password protection on incoming telnet sessions?
- line vty 0 4
- What command uses Cisco proprietary encryption process to alter the password character string?
- enable secret password
- If you do not configure a router name, what is the default name?
- What mode must you be in to change the routers name?
- Global Config
- What does the command banner motd allow you to do?
- Configure a message-of-the-day banner to be displayed on all connected terminals at login
- What delivery method does IP use?
- Best Effort
- What are three reasons data may fail to reach its destination?
- 1. Hardware Failure
2. Improper configuration
3. Incorrect routing info
- What does IP use to notify the sender that the message couldnt be delivered?
- What type of message provides information or configuration parameters to hosts?
- Control messages
- What component of TCP/IP notifies the sender that a data transmission has failed?
- What is the acronym for Internet Control Message Protocol?
- Does a router know the exact path a datagram took to get to the router?
- What is the ONLY information a router has about a datagram?
- Only the source and destination IP address of the datagram
- Does ICMP correct network problems?
- Does ICMP notify the intended receiver that there was a problem delivering the packet?
- Why dont error created by ICMP messages generate their own ICMP message?
- error reports could generate more error reports, causing increased congestion on an already ailing network
- What 3 addresses are needed in TCP/IP configuration if datagrams are to travel outside the local network
- 1. IP Address
2. Subnet mask
3. Default gateway
- What two things must a router have in order to send datagrams?
- 1. TCP/IP properly configured on it's interfaces
2. An appropriate routing protocol
- What is the term that is used when a destination network is not accessable?
- Unreachable network
- What happens if the destination device recieves the ICMP echo request?
- It formulates an echo reply message to send back to the source of the echo request
- What command initiates an echo request?
- If an echo request is succesful between the source and destination what does that mean.
- This confirms ip connectivity betweeen the two devices
- What would be created if two routers continually route a datagram back and forth?
- Loop - travels in circles
- What is the maximum hop count for RIP?
- What does TTL stand for?
- Time to Live
- What 3 fields are common to all ICMP messages?
- 1. Type
- What are four reasons datagrams might not make it to their destination?
- 1. Hardware failures
2. Improper protocol configuration
3. down interfaces
4. Incorrect routing information
- If a "3" appears in the type field what does that mean?
- Destination Unreachable
- What does the "code value" indicate?
- The reason a packet could not be delivered
- What is usually needed to forward a datagram from a token-ring to an ethernet network?
- Packet fragmentation
- If a datagram header has an error what will a device like a router do?
- It sends an ICMP type 12 parameter problem message to the source
- When the code value of teh problem message reaches 0, what will the pointer field indicate?
- the octet of the datagram that produced the error
- Why is a control message sent?
- To inform hosts of conditions such as network congestion or a better gateway.
- How are ICMP control messages sent?
- Inside IP datagrams
- What is another term for "gateway"
- What is the only device that can initiate a Redirect/Change request message?
- How is a redirect/change configured on a Cisco router?
- It's the default
- What allows a host to ask for the current time according to the remote host?
- The ICMP timestamp message request
- What are the 2 type fields on an ICMP time stamp message?
- 13 (Timestamp request) or
14 (Timestamp reply)
The code field value is always set to 0, because there are no additional parameters available.
- What 3 things are contained in the ICMP timestamp reply message
- 1. the originate timestamp
2. the receive timestamp
3. transmit timestamp
- What 2 things affect true transit time?
- 1. Traffic
2. Congestion on the network
- What 2 protocls are now used to allow a host to find its network number?
- 1. BOOTP
- What type of message is sent out when a host doesnt know the network address?
- Address mask request
- What is the mulicast address for router discovery?
- What happens if a router receives a multicast request but isnt configured for multicasting?
- It doesnt answer the request
- If the default gateway is missing, what message is genereated by the host?
- router solicitation
- What happens when there is too much congestion on a network?
- Packets are dropped
- Why dont Cisco routers send source quench messages(by default)?
- because the source-quench message may itself add to the network congestion
- What type of offices might use source quench messages
small office home office
- What is the standard for internetwork communications?
- What is the transport protocol for the internet?
- What is the function of the TCP/IP protocol suite?
- Responsible for the reliable transport and regulation of data flow from source to destination
- Prior to data transmission, the 2 communicating hosts go through a synchronization process to establish a virtual connection for each session between hosts. This process is called what?
- Three way hand shake
- Describe the process of a three way hand shake?
- 1. The source host sends the destination host a request for communication. This is done by sending a sequence number
2. The destination host sends back and Acknowledgement of the sequence number and then adds a 1 to it and sends it back.
3. The source host acknowledges the sequences number+1 that the destination host sent and begins transmitting
- DoS stands for?
- Denial of Service attack
- Describe SYN flooding?
- SYN flooding exploits the normal three way handshake and causes targeted devices to acknowledge to source addresses that will not complete the handshake
- Describe DoS attack?
- the hacker initiates a SYN but spoofs the source IP address. Spoofing is a term used when the receiving device replies to a non-existant, unreachable ip address and then is placed in a wait state until it recieves the final acknowledgement from the initiator
- What are some defense mesures for SYN flooding and DoS attacks?
- system administrators may decrease the connection timeout period and increase the connection queue size. Software also exists that can detect these type of attacks and initiate defensive measures
- Describe how windows provides flow control?
- data must be broken into smaller pieces to allow for proper data transmission
- What is the purpose of TCP applying sequence numbers to segments?
- so that the recieving node can reassemble bytes in the correct order
- What does TCP do if a sequence number is missing in a series?
- That segment is retransmitted
- TCP uses positive acknowledgement and retransmission (PAR) for what?
- to control data flow and confirm data delivery
- Name the field responsible for trancking of transmitted and received bytes?
- the Acknowledgment Number field
- What two protocols does the Transport layer provide?
- 1. TCP
- What layer 3 protocol is connectionless?
- Which protocol is a connection oriented reliable protocol?
- What protocol is connectionless and unreliable?
- What advantage does UDP provide over TCP?
- TCP provides services for what applications?
- 1. FTP
- UDP is the transport layer protocol used by what applications?
- 1. DNS
- UDP is unreliable - so what layer provides error detection?
- UDP does not use windowing or ACK's so APPLICATION LAYER protocols must provide error detection
- What are port numbers used to keep track of?
- the different conversations that cross the network at the same time
- Both TCP and UDP use _________ to pass information to upper layers?
- port or socket numbers
- What port is used for FTP application?
- What port numbers are used for public applications?
- Below 255
- What is port number 53 used for?
- What is the port used for telnet?
- The IP address gets the packet to the _______?
The TCP or UDP port number guarantees that the packet is passed to the correct ___________?
- correct server
- Port numbers in the range of 0 - 1023 used to select proper applications are considered public port numbers and are controlled by ___________?
- Internet Assigned Numbers Authority (IANA)
- IP addresses gets the packet to the correct server but ___________ GUARANTEES the packet is passed to the correct application?
- TCP or UDP
- Be able to determine the difference between TCP segments and UDP segments What information do UDP segments not contain?
- No sequence numbers or Acknowledgement fields
- List the 3 categories of port numbers.
- 1. Well known ports
2. Registered ports
3. dynamic or private ports
- _______________ are located at he transport layer and are serviced by the network layer?
- Port numbers
- The Network layer assigns the logical address or ____________, and is then serviced by the Data Link layer, which assigns the physical address or the ______________.
- IP address
- What is a sequential list of permit or deny statements that apply to addresses or upper layer protocols?
- An ACL
- What are two things a router can do with a packet?
- Accept or Deny
- How are ACL's defined?
- On a per-protocol, per direction (in or out), or per port basis
- What happens to packets if an ACL is not configured on a router?
- all packets passing through the router will be allowed on all parts of the network.
- Where are packets either accepted or rejected due to an ACL?
- at the interface
- How does a router read an ACL?
- From top to bottom
- What happens to the ACL statements once a match is found in the list?
- the accept or reject action is performed and no other ACL statements are checked
- What happens if additional condition statements are needed in an access list.
- The entire ACL must be deleted and recreated with new condition statements.
- What is placed at the end of EVERY ACL?
- Implicit Deny Any statement
- What mode must you be in to create an ACL?
- Global Config
- What are the 2 steps in creating an ACL
- 1. Create the ACL
2. Apply it to an Interface
- What are 2 directions ACL's can be placed?
- Where should a standard ACL be placed?
- Closest to the destination
- Where should an extended ACL be placed
- Closest to the source
- What happens if no match is found on an ACL list?
- The packet is denied
- What does a 1 mean in wildcard masking?
- What does a 0 mean in wildcard masking?
- What IP Address and subnet mask will the word any substitute for?
- 0.0.0.0 255.255.255.255
- What command shows ALL the ACLs on a router
- show access-lists
- What do standard ACL's check?
- Source IP address
- What is the default wildcard mask?
- What 4 things can an Extended ACL check?
- 1. Source Address
2. Destination Packet Address
4. Port number
- What type of echo packet is sent to the sender if the packet is discarded?
- destination was unreachable
- Can you use the wildcard host or any keywords in the command?
- What does the ip access-group command link?
- an existing extended ACL to an interface
- What version of CISCO IOS allowed for named ACL's?
- What mode must you be in to configure a named ACL?
- Global Config
- Where do you place Extended ACLs?
- As close to the source as possible
- Where do you place standard ACLs?
- As close to the destination as possible
- Who does a firewall try to keep out the intranet?
- intruders that come from the global internet
- Where are most firewalls placed?
- between the internal network and an external network, such as the internet
- What are routers that are situated on the boundries of a network?
- Border routers
- What 2 types of ACLs are used on packets traveling through a router?
- What are the numbers of the virtual ports on a router
- 0, 1, 2, 3, 4
- Why should identical restrictions be placed on all vty lines?
- Its impossible to control which line a user will connect on
- What does a router do when it determines that a route is the best path to a destination?
- It adds that route to its routing table.
- What are the 2 most time consuming jobs of a network administrator?
- Network testing and troubleshooting
- What type of equipment causes the most difficult network problems?
- What is the function of a router?
- To determine the best path from a source to a destination
- What do routers read to make packet forwarding decisions?
- Contents of their IP routing table
- What does the command show ip route display?
- The contents of their IP routing table
- What is a manually configured route called?
- Static Route
- What is a route that can change automatically as neighboring routes update each other with new information?
- Dynamic Route
- What is used when the router is unable to match a destination network with an entry in its routing table?
- Default route
- What command establishes a default route in networks using dynamic routing protocols?
- ip route 0.0.0.0 0.0.0.0
- What layer determines the best path for a packet?
- Network Layer (Layer 3)
- What device determines the best path and forwards the packet from an incoming interface to an outgoing interface
- what address is used to get packets from source to destination?
- Layer 3 Address
- What address never changes no matter how many hops a packet takes?
- Source and Destination IP Address
- What address changes at each hop or router?
- MAC Address
- What metric does rip v1 use?
- Hop Count
- What metric is better higher or lower
- What layer should you start with when testing network problems?
- Layer 1
- What is the most common problem on IP networks?
- Errors in the addressing scheme
- What is the most important part of troubleshooting?
- What layer would a transciever problem be at?
- Layer 1
- What layer would an improperly configured serial interface be at?
- Layer 2
- What layer would an incorrect IP address be?
- Layer 3
- What command is used to test connectivity
- What is another name for the "indicator" light on a NIC card that indicates a valid connection
- Link Light
- What should you do if the interface has indicator lights that do not show a valid connection?
- Check for faulty or incorrect cabling
- What 3 things are displayed when a ping packet finds a specified system and returns?
- Minimum, Maximum, and Average time it takes for a packet to find a specified system and return
- What will the command show ip protocol show?
- Shows the current state of the active routing protocols
- What does IGRP use to balance the load on multiple links?
- What does 5 exclamation points indicate when performing a ping?
- A successful connection
- What command would you use to perform more extensive ping tests?
- Extended Ping
- Which ICMP message type notifies the source host that a receiving host or network is not available?
- Destination Unreachable
- What layer does Telnet test
- All Layers
- What line from show interfaces output would indicate a layer 2 problem?
- The line that says
Interface UP Line protocol DOWN
- What would an Increasing number of Carrier transitions counts on a serial link indicate?
- Bad Link or defective CSU/DSU
- What are messages sent by one network device to inform another network device that the virtual circuit between the two is still active?
- Who does CDP allow you to discover information about?
- Directly connected Cisco devices
- What command is used to discover routes that packets take when traveling to their destination?
- What command shows the entries for all known networks and subnetworks, and how that information was learned
- show ip route
- what commadn would identify a router that is delivering bad router information?
- Show IP protocols
- What command would allow you to check a cable connection if you were in LA and a router was in New York?
- Show controllers
- What command will turn off all diagnostic output?
- no debug all
- What command will show what is being examined by a debug command?
- show debugging
- MAC Addresses are how many bits in Length?
- Describe communicaton between 2 devices on a LAN
- The source device encapsulates data in a frame with the MAC address of the destination device and then transmits it. Everyone on the LAN sees it but the devices with non matching addresses otherwise ignore the frame.
- What are some functions associated with Frames
- 1. Identifies which computers are communicating with one another
2. Signals when communication between individual computers begins and when it ends
3. Flags corrupted Frames
- Media Access Control Refers to what?
- Rules that determine which computer on a shared-medium is allowed to transmit the data
- How do you describe CSMA/CD networks?
- One node's transmission traverses the entire network and is received and examined by every node.
- What are the important Data Link Layer (Layer 2) functions?
- Logical Link Control
Media Access Control
- What is true of a deterministic MAC protocol?
- It allows hosts to "take turns" sending data
- Fast Ethernet Supports up to what transfer rate?
- 100 Mbps
- What are the 2 Gigabit over fiber cable specifications?
- What is the transmission medium for 1000BASE-SX?
- Short-wave laser over multimode fiber
- 4D-PAM5 encoding method is used in which Gigabit ethernet?
- What happens when 1000BASE-T sends and receives data in full-duplex mode on the same conductor?
- A permanent collision on the wire
- What is the maximum transmission distance supported by 10 Gigabit Ethernet?
- 40 Kilometers
- What are 3 features of microsegmentation?
- 1. It enables dedicated access
2. It supports multiple conversations at any given time
3. It increases the capacity for each workstation connected to the network
- What do LAN switches use to make forwarding decisions?
- MAC Addresses
- What best describes one function of Layer 3, the network layer, in the OSI model?
- It determines the best path for traffic to take through the network.
- What function allows routers to evaluate available routes to a destination and to establish the preferred handling of a packet?
- Path Determination
- How does the network layer forward packets from the source to the destination?
- By using A routing table
- What 2 parts of a network layer address do routers use to forward traffic through a network?
- Network address and destination IP address
- What best describes a routed protocol?
- Its address provides enough information to allow a packet to be forwarded from host to host.
- What best describes a routING protocol?
- A protocol that accomplishes routing throgh the implementation of an algorithm
- Whats an advantage of distance vector algorithms?
- They are computationally simple
- What describes Link State algorithms
- It recreates the exact topology of the entire network
- Why do routing loops occur?
- Slow convergence occurs after a modification to the internetwork.
- Describe the concept describing EIGRP as a balanced hybrid routing protocol?
- Being that EIGRP is a distance vector routing protocol, it determines best paths, but topology changes trigger routing updates
- What is a network with only one path to a router called
- Stub network
- What best describes a default route?
- Route used when the destination network is not listed explicitly in the routing table
- What kind of entries does a router initally refer to?
- Entries about networks or subnets that are directly connected
- What are exterior routing protocols used for?
- To communicate between autonomous systems.
- If you suspect that one of the routers connected to your network is sending bad routing information what command would you use to check?
- router> show ip protocol
- Why would you display the routing table?
- To identify destination network addresses and next-hop pairs
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