CCENT Review
Put the following descriptions in order from Layer 7 to Layer 1 and give the name of each layer
Layer
Application
Presentation
Session
Transport
Network
Data Link
Physical
Which addresses are valid host IP addresses given the
network 172.16.32.8 subnet mask 255.255.255.248?
Which addresses are valid host IP addresses given the
network 172.16.32.8 subnet mask 255.255.255.248?
• Shortcut 256-248=8
• Range 8 in last octet
• 172.168.32.8 – 172.168.32.15
192.168.102.65/27
32 hosts on each subnet
192.168.101.64-95
73 ok
81 ok
192.168.102.97/27
32 hosts on each subnet
192.168.101.96-127
123 ok
148 OUT OF RANGE
• A network host has the IP address
10.250.206.55/20. How many more network
devices can be added to this same
subnetwork?
• A network host has the IP address
10.250.206.55/20. How many more network
devices can be added to this same
subnetwork?
• /20 =
• 11111111.11111111.11110000.00000000
• NOTE - 255.255.XXX.0 (XXX – interesting octet)
• 2 ^ 12 = 4096
• 4096 – 3 = 4093
To which subnetwork does this packet
belong? 10.149.177.135/14
To which subnetwork does this packet
belong? 10.149.177.135/14
•
/14 subnet mask 255.252.0.0
• 10.149.177.135
• 00001010.10010101.10110001.10000111 AND
• 11111111.11111100.00000000.00000000 EQUALS
• 00001010.10010100.00000000.00000000 binary
• 10.148.0.0 Network
• 10.151.255.255 Broadcast
The router receives a packet with the destination
address of 172.16.30.79. To which subnetwork does
this packet belong?
172.16.0.0/21
172.16.20.0/21
172.16.24.0/21
172.16.28.0/21
172.16.32.0/21
The router receives a packet with the destination address of
172.16.30.79. To which subnetwork does this packet belong?
/21 = 11111111.11111111.11111000.00000000
2^3=8
172.16.0.0/21 = 172.16.0.0 – 172.16.7.255
172.16.20.0/21 20 not a multiple of 8
172.16.24.0/21 = 172.16.24.0 – 172.16.31.255
172.16.28.0/21 28 not a multiple of 8
172.16.32.0/21 = 172.16.32.0 – 172.16.39.255
How many collision and broadcast domains are show in the following network topology?
If all the switches have the default configuration, how many collision and broadcast
domains are show in the following network topology?
Collision – 12
Broadcast – 3
What is the function of the router in
this topology?
What is the function of the router in this topology?
Determines the path to send the message to get to a destination network.
Each port, or interface, on a router connects to a different local network.
Every router contains a table of all locally-connected networks and the interfaces that connect to them.
These routing tables can also contain information about the routes, or paths, that the router uses to
reach other remote networks that are not locally attached.
When a router receives a frame, it decodes the frame to get to the packet containing the destination IP
address.
It matches the address of the destination to all of the networks that are contained in the routing table. If
the destination network address is in the table, the router encapsulates the packet in a new frame in
order to send it out. It forwards the new frame out of the interface associated with the path, to the
destination network.
Routers contain broadcasts.
Define Default Gateway and discussed how it would be used in this topology.
The default gateway address is the address of the router interface connected to the same local
network as the source host.
All hosts on the local network use the default gateway address to send messages to the router.
Once the host knows the default gateway IP address, it can use ARP to determine the MAC
address.
The MAC address of the router is then placed in the frame, destined for another network.
• What tables are maintained by routers?
• What tables are maintained by routers?
If the router cannot determine where to forward a message, it will drop it.
Configure a routing table with a default route to keep a packet from being dropped.
A default route is the interface through which the router forwards a packet
containing an unknown destination IP network address.
Identify the following as a unicast, broadcast or multicast.
A company has an 802.11b wireless access point installed. Which type of wireless
NIC is a valid standards-based one but will not work in this environment?
A company has an 802.11b wireless access point installed. Which type of wireless
NIC is a valid standards-based one but will not work in this environment?
802.11a
Match the wireless term to its definition.
Term
Definition
Service Set Identifier
uses the MAC address to identify which
devices are allowed to connect to the wireless
network
Extensible Authentication Protocol
the user, not just the host, must provide a
username and password which is checked
against the RADIUS database for validity
Open Authentication
used to tell wireless devices which WLAN they
belong to and with which other devices they
can communicate
Pre-Shared Key
wireless devices do not require authentication
Wired Equivalent Privacy
generates new, dynamic keys each time a
client establishes a connection with the AP
MAC Address Filtering
one-way authentication, the host
authenticates to the AP, does not authenticate
the AP to the host, nor does it authenticate the
actual user of the host
WiFi Protected Access
uses pre-configured keys to encrypt and
decrypt data
Match the wireless term to its definition.
Term
Definition
Service Set Identifier
uses the MAC address to identify which
devices are allowed to connect to the wireless
network
Extensible Authentication Protocol
the user, not just the host, must provide a
username and password which is checked
against the RADIUS database for validity
Open Authentication
used to tell wireless devices which WLAN they
belong to and with which other devices they
can communicate
Pre-Shared Key
wireless devices do not require authentication
Wired Equivalent Privacy
generates new, dynamic keys each time a client
establishes a connection with the AP
(encrypts)
MAC Address Filtering
one-way authentication, the host
authenticates to the AP, does not authenticate
the AP to the host, nor does it authenticate the
actual user of the host
WiFi Protected Access
uses pre-configured keys to encrypt and
Once a hacker gains access to the network, what
are the four types of threats?
Once a hacker gains access to the network, what
are the four types of threats?
•
•
•
•
Information theft
Identity theft
Data loss / manipulation
Disruption of service
What command is described below?
• Tests the accessibility of a specific IP address
• Sends an ICMP (Internet Control Message
Protocol) echo request packet to the
destination address and then waits for an
echo reply packet to return from that host
• Output indicates whether the reply was
received successfully and displays the roundtrip time for the transmissions
What command is described below?
Answer - ping
• Tests the accessibility of a specific IP address
• Sends an ICMP (Internet Control Message
Protocol) echo request packet to the
destination address and then waits for an
echo reply packet to return from that host
• Output indicates whether the reply was
received successfully and displays the roundtrip time for the transmissions
Draw a picture using each of the
following cables.
Describe what has to happen for this
packet to continue.
Describe what has to happen for this
packet to continue.
Describe what has to happen for this
packet to continue.
Describe what has to happen for this
packet to continue.
Which type of Network Address Translation allows a host on a public
network consistent access to a specified private inside host?
A. Static NAT
B. Dynamic NAT
C. PAT
Which type of Network Address Translation allows a host on a public
network consistent access to a specified private inside host?
A. Static NAT
B. Dynamic NAT
C. PAT
Which addresses are “inside global” addresses?
Which addresses are “inside global” addresses?
Answer - 198.133.219.33 – 198.133.219.62
Which two items are required for initial configuration of Cisco
routers if the IOS command-line interface is used
Which two items are required for initial configuration of Cisco
routers if the IOS command-line interface is used
Answer – Rollover cable and terminal emulation
Fill in the blanks.
The router bootup process has three stages.
1.
Perform _________________________ and load the bootstrap program.
•
The _________ is a process that occurs on almost every computer when it boots up. _________ is used to test the
router hardware. After _______________, the bootstrap program is loaded.
2.
Locate and load the Cisco IOS software.
•
The bootstrap program locates the Cisco IOS software and loads it into RAM. Cisco IOS files can be located in one
of three places: ____________, _____________, or another location indicated in the startup configuration file. By
default, the Cisco IOS software loads from _________ memory. The configuration settings must be changed to
load from one of the other locations.
3.
Locate and execute the _____________ configuration file or enter setup mode.
•
After the Cisco IOS software is loaded, the bootstrap program searches for the ____________ configuration file in
NVRAM. This file contains the previously saved configuration commands and parameters, including interface
addresses, routing information, passwords, and other configuration parameters.
•
If a configuration file is not found, the router prompts the user to enter _______ mode to begin the configuration
process.
•
If a __________ configuration file is found, it is copied into RAM and a prompt containing the host name is
displayed. The prompt indicates that the router has successfully loaded the Cisco IOS software and configuration
file.
Fill in the blanks.
The router bootup process has three stages.
1.
Perform Power-on self test (POST) and load the bootstrap program.
•
The POST is a process that occurs on almost every computer when it boots up. POST is used to test the router
hardware. After POST, the bootstrap program is loaded.
2. Locate and load the Cisco IOS software.
•
The bootstrap program locates the Cisco IOS software and loads it into RAM. Cisco IOS files can be located in one
of three places: flash memory, a TFTP server, or another location indicated in the startup configuration file. By
default, the Cisco IOS software loads from flash memory. The configuration settings must be changed to load from
one of the other locations.
3. Locate and execute the startup configuration file or enter setup mode.
•
After the Cisco IOS software is loaded, the bootstrap program searches for the startup configuration file in
NVRAM. This file contains the previously saved configuration commands and parameters, including interface
addresses, routing information, passwords, and other configuration parameters.
•
If a configuration file is not found, the router prompts the user to enter setup mode to begin the configuration
process.
•
If a startup configuration file is found, it is copied into RAM and a prompt containing the host name is displayed.
The prompt indicates that the router has successfully loaded the Cisco IOS software and configuration file.
• NVRAM – running-config or startup-config
• RAM – running-config or startup-config
• ROM – running-config or startup-config
• NVRAM – running-config or startup-config
• RAM – running-config or startup-config
• ROM – running-config or startup-config
Router(config)# hostname South South(config)# exit South# copy running-config
startup-config
• A network administrator can ping the Denver
router, but gets a 'Password Required but
None Set' message when trying to connect
remotely via Telnet. Which command or
sequence of commands must be applied to
the Denver router to allow remote access?
• A network administrator can ping the Denver
router, but gets a 'Password Required but None
Set' message when trying to connect remotely via
Telnet. Which command or sequence of
commands must be applied to the Denver router
to allow remote access?
• Router(config)# line vty 0 4 Router(config-line)#
login Router(config-line)# password cisco
• Which command is used to create an
encrypted password that restricts access to
the privileged EXEC mode of a Cisco router?
• RouterA(config)# enable secret cisco
• Describe the command ip route 192.168.7.24
255.255.255.248 192.168.7.9?
• What are two ways that TCP uses the
sequence numbers in a segment?
• What are two ways that TCP uses the
sequence numbers in a segment?
• Missing segments at the destination,
reassemble the segments
• Characterize UDP with 3 words. Fill in the
blank. UDP is __________________.
• Characterize UDP with 3 words. Fill in the
blank. UDP is __________________.
• Connectionless
• Faster (fast transport of data at Layer 4)
• Dependent (on application layer protocols)
• Unguaranteed (works well when an
application does not need guarantee of
delivery of data)