Quiz:
1.Which layer of the OSI model is responsible for converting frames into bits and bits
into frames?
a. Physical
b. Network
c. Transport
d. LLC sublayer
e. Data link
The data link layer performs bit conversion to pass to the MAC sublayer.
2.Routing occurs at what layer of the OSI model?
a. Physical
b. Network
c. Transport
d. LLC sublayer
e. Data link
Routing is a Layer 3 (network layer) function.
3.Bridging occurs at what layer of the OSI model?
a. Physical
b. Network
c. Transport
d. Data link
The data link layer is where bridging is performed.
4.Which of the following is
not
part of the OSI model?
a. Network layer
b. Physical layer
c. Operational layer
d. Application layer
The operational layer is not one of the seven OSI layers. The OSI model layers are
physical, data link, network, transport, session, presentation, and application.
5.IP operates at what layer of the OSI model?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
e. Layer 5
f. Layer 6
g. Layer 7
IP operates at the network layer (Layer 3) and provides a path to a destination.
6.On which layer of the OSI model is data commonly referred to as segments?
a. Layer 4
b. Layer 3
c. Layer 2
d. Layer 1
The data on Layer 4 is commonly referred to as segments.
7.On which layer of the OSI model is data commonly referred to as packets?
a. Layer 1
b. Layer 2
c. Layer 4
d. Layer 3
The data on Layer 3 is commonly referred to as packets.
8.Which layer of the OSI model transmits raw bits?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
At Layer 1, the lowest layer of the OSI model, bits are transferred across the wire.
9.Which of the following protocols is
not
routable?
a. IP
b. IPX
c. NetBEUI
d. NetBIOS
NetBEUI is not a routed protocol and must be bridged.
10.Which of the following is
not a required step to enable FastEther Channel (FEC)?
a. Ensure that all ports share the same speed at 10 Mbps.
b. Ensure that all ports share the same parameter such as speed.
c. Ensure that all ports operate at 100 Mbps.
d. Only eight ports can be bundled into a logical link or trunk.
FEC uses full-duplex Fast Ethernet (100 Mbps) links.
11.How is FastEther Channel best defined?
a. A bundle of 10-Mbps ports on a switch
b. Another name for half duplex 100 Mbps
c. Not available on Cisco Catalyst switches
d. The ability to bundle 100 Mbps ports into a logical link
e. Only supported with Gigabit ports
The FastEther Channel feature bundles 100 Mbps Fast Ethernet ports into a logical
link between two devices, such as Catalyst switches.
12.On what OSI layer does bridging occur?
a. Layer 1
b. Layer 2
c. Layer 3
d. Both Layer 1 and 2
Bridging occurs at the data link layer (Layer 2) of the OSI model.
13.In spanning tree, what is a BPDU?
a. A break protocol data unit
b. A routable frame
c. A bridge protocol data unit
d. A frame sent out by end stations
BPDU is a bridge protocol data unit.
14.An incoming frame on a Layer 2 switch is received on port 10/1 on a Catalyst 5000. If the
destination address is known through port 10/2, what happens?
a. The frame is discarded.
b. The frame is sent via port 10/2.
c. The frame is broadcast to all ports on the switch.
d. The frame is sent back via 10/1.
e. None of the above.
The destination MAC address has already been discovered through port 10/2, so the
frame will only be sent to the known port or slot 10, port 2.
15.Which of the following are the four possible states of spanning tree?
a. Listening, learning, blocking, broadcasting
b. Listening, learning, blocking, connecting
c. Discovering, learning, blocking, connecting
d. Listening, learning, blocking, forwarding
The four states of spanning tree are listening, learning, blocking, and forwarding.
16.How many bits make up an IP address?
a. 64 bits
b. 48 bits
c. 32 bits
d. 24 bits
e. 8 bits
IP addresses for IPv4 are 32 bits in length.
17.Identify the broadcast address for the subnet 131.108.1.0/24.
a. 131.108.1.1
b. 131.108.1.254
c. 131.108.1.255
d. 131.108.1.2
e. More data required
131.108.1.0/24 is a Class B address with a Class C mask, and the all (all binary 1s)
broadcast address is 131.108.1.255 (11111111).
18.Convert the following address to binary:
131.1.1.1/24
a. 10000011.1.1.1
b. 10000011.00000010.1.1
c. 10000011.1.1.01010101
d. 10000011.1.1.11111111
131.108.1.1 in binary is 10000011.00000001.00000001.00000001 or 10000011.1.1.1
19.How many subnets are possible in VLSM if the Class C address 131.108.255.0 is used
with the subnet mask 255.255.255.252 in the fourth octet field?
a. None
b. 100
c. 255
d. 254
e. 253
f. 252
g. 64
h. 62
2
6
–2 = 64–2 = 62.
20.How many hosts are available when a /26 subnet mask is used?
a. 254
b. 62
c. 64
d. 126
2
6
–2 = 64–2 = 62.
21.How many hosts are available in a Class C or /24 network?
a. 255
b. 254
c. 253
d. 0
e. More data required
A Class C or /24 network has 2
8
–2 = 256–2 = 254 addresses available for host devices.
22.You require an IP network to support at most 62 hosts. What subnet mask will accomplish
this requirement?
a. 255.255.255.255
b. 255.255.255.252
c. 255.255.255.224
d. 255.255.255.192
e. 255.255.255.240
62 hosts require 62+2 = 64 addresses. This needs 6 bits borrowed from the subnet
mask. In binary, that number is 11000000.
23.Which of the following are multicast addresses? (Choose all that apply.)
a. 224.0.0.5
b. 224.0.0.6
c. 221.0.0.5
d. 192.1.1.1
e. 131.108.1.1
224.0.0.5 and 224.0.0.6 are multicast addresses.
24.Which of the following routing protocols does not support VLSM?
a. RIPv1
b. RIPv2
c. OSPF
d. EIGRP
e. BGP
RIP version I is classful and does not carry subnet masks in routing updates.
25.What is the source TCP port number when a Telnet session is created by a PC to a Cisco
router?
a. 23
b. Not a known variable
c. 21
d. 20
e. 69
The source TCP port is a random number; the destination port is 23.
26.What best describes the ARP process?
a. DNS resolution
b. Mapping an IP address to a MAC address
c. Mapping a next-hop address to outbound interface on a Cisco router
d. Both a and b
ARP maps an IP address to a MAC address.
27.If two Cisco routers are configured for HSRP and one router has a default priority of 100
and the other 99, which router assumes the role of active router?
a. The default priority cannot be 100.
b. The router with a higher priority.
c. The router with the lowest priority.
d. Neither router because Cisco routers do not support HSRP; only clients do.
The highest priority assumes the role of active router.
28.A Cisco router has the following route table:
R1#show ip route
131.108.0.0/16 is variably subnetted, 17 subnets, 2 masks
C 131.108.255.0/24 is directly connected, Serial0/0
C 131.108.250.0/24 is directly connected, Serial0/1
O 131.108.254.0/24 [110/391] via 131.108.255.6, 03:33:03, Serial0/1
[110/391] via 131.108.255.2, 03:33:03, Serial0/0
R 131.108.254.0/24 [120/1] via 131.108.255.6, 03:33:03, Serial0/1
[120/1] via 131.108.255.2, 03:33:03, Serial0/
What is the preferred path to 131.108.254.0/24? (Choose the best two answers.)
a. Via Serial 0/0
b. Via Serial 0/1
c. None
d. To null0
OSPF is chosen because of the lower administrative distance of 110 compared to
RIP’s 120. Also notice OSPF load balancing between Serial0/0 and Serial0/1. (The
written examination always advises you how many answers to select. Practice on the
CD provided.)
29.IP RIP runs over what TCP port number?
a. 23
b. 21
c. 69
d. 520
e. None of the above
IP RIP does not use TCP port numbers; it uses UDP.
30.IP RIP runs over what UDP port number?
a. 23
b. 21
c. 69
d. 520
UDP 520
31.An OSPF virtual link should .
a. Never be used
b. Allow nonpartitioned areas access to the backbone
c. Allow partitioned areas access to the backbone
d. Not be used in OSPF, but in ISDN
Virtual links allow access to areas not directly connected to the backbone or
partitioned areas.
32.What is the BGP version most widely used today?
a. 1
b. 2
c. 3
d. 4
e. 5
f. 6
BGP4.
33.What is the destination port number used in a Telnet session?
a. 23
b. 69
c. 21
d. 161
Telnet, an application layer protocol, uses destination port 23.
34.In what fields does the IP checksum calculate the checksum value?
a. Data only
b. Header and data
c. Header only
d. Not used in an IP packet
The IP checksum calculation only covers the IP header.
35.The TCP header checksum ensures integrity of what data in the TCP segment?
a. The data only.
b. The header only.
c. The data and header.
d. There are no TCP header checksums; IP covers the calculation.
The TCP checksum calculation covers the TCP header and data.
36.ISDN BRI channels are made up of what?
a. 1
64 kbps channel and one D channel at 64 kbps
b. 2
64 kbps channels and one D channel at 64 kbps
c. 2
64 kbps channels and one D channel at 16 kbps
d. 32
64 kbps channels and one D channel at 16 kbps
ISDN basic rate interface (BRI) is two 64-kbps data channels and one signaling
channel (D Channel at 16 Kb).
37.What services can ISDN carry?
a. Data only
b. Data and voice only
c. Voice and video
d. Data, voice, and video
ISDN supports data, video, and voice.
38.Place the following steps in the correct order for PPP callback, as specified in RFC 1570.
1. A PC user (client) connects to the Cisco access server.
2. The Cisco IOS Software validates callback rules for this user/line and disconnects the
caller for callback.
3. PPP authentication is performed.
4. Callback process is negotiated in the PPP link control protocol (LCP) phase.
5. The Cisco Access Server dials the client.
a. 1, 2, 3, 4, 5
b. 1, 3, 2, 5, 4
c. 1, 4, 5, 3, 2
d. 5, 4, 3, 2, 1
RFC 1570 dictates how PPP callback is to be followed. For more information, refer
to www.cis.ohio-state.edu/cgi-bin/rfc/rfc1570.html.
39.What hardware port is typically designed to connect a Cisco router for modem access?
a. The console port
b. The vty lines
c. The auxiliary port
d. The power switch
e. The Ethernet interface
The auxiliary port on Cisco routers can be used for modem access. The console port
can also be used but, typically, the Aux port is applied for remote access or dialup
access for network failures.
40.The AS5300 series router can support which of the following incoming connections?
a. Voice
b. Dialup users via PSTN
c. ISDN
d. All the above
The AS5300 series router can support both digital (ISDN) and analogue connections,
and also supports voice traffic.
Q&A
1What are the seven layers of the OSI model?
Answer: The seven layers of the OSI model are as follows:
•Application
•Presentation
•Session
•Transport
•Network
•Data link
•Physical
2What layer of the OSI model is responsible for ensuring that IP packets are routed from
one location to another?
Answer: The network layer is primarily responsible for routing IP packets from one
destination to another.
3What mechanism is used in Ethernet to guarantee packet delivery over the wire?
Answer: Carrier Sense Multiple Access/Collision Detection (CSMA/CD) is the
Ethernet mechanism used to ensure that when devices detect collisions, other devices
on the segment are sent a jam signal. CSMA/CD ensures that when collisions occur,
other devices (such as PCs or routers) back off (do not transmit) for a specified
period of time. When a device receives a jam signal, it will wait a random amount of
time to retransmit. This lowers the chance of another collision. All devices that detect
a jam signal can transmit up to 16 times before sending an error message to the
application layer.
4Name two physical characteristics of 10BaseT?
Answer: 10BaseT is an Ethernet physical layer standard that defines a maximum
length of 100 m and a network speed of 10 Mbps.
5What Catalyst command displays the bridging or CAM table on a Cisco 5000 series
switch?
Answer: show cam dynamic
6What are the possible states of spanning tree?
Answer: The possible states of spanning tree are as follows:
•Disabled—The port is not participating in spanning tree and is not active.
•Listening—The port has received data from the interface and will listen for
frames. In this state, the bridge only receives data and does not forward any
frames to the interface or to other ports.
•Learning—In this state, the bridge still discards incoming frames. The source
address associated with the port is added to the CAM table. BPDUs are sent and
received.
•Forwarding—The port is fully operational; frames are sent and received.
•Blocking—The port has been through the learning and listening states and,
because this particular port is a dual path to the root bridge, the port is blocked
to maintain a loop-free topology.
The order of spanning tree states is listening, then learning, and, finally, forwarding
or blocking. Typically, each state takes around 15 seconds on Cisco Catalyst switches.
7FastEther Channel (FEC) allows what to occur between Cisco Catalyst switches?
Answer: FEC is a Cisco method that bundles 100 MB/s fast Ethernet ports into a
logical link between Cisco Catalysts switches, such as the Catalyst 5000 or 6000
series switches.
Up to four ports can be bundled together to scale bandwidth up to 800 Mbps.
8What field in the IP packet guarantees data delivery?
Answer: The IP frame format has no settings that guarantee packet delivery, so IP
is termed connectionless. The error check is only performed on the IP header fields,
not the data in the packet.
9Name some examples of connection-orientated protocols used in TCP/IP networks.
Answer: Connection-orientated protocols include TCP, FTP, and Telnet.
10 Given the address, 131.108.1.56/24, what are the subnet and broadcast addresses? How
many hosts can reside on this network?
Answer: The subnet is 131.108.1.0 and the broadcast address is 131.108.1.255. The
number of hosts is defined by the formula 28-2=256-2=254.
11 How many hosts can reside when the subnet mask applied to the network 131.108.1.0 is
255.255.255.128 (or 131.108.1.0/25)?
Answer: The number of hosts is 27-2=128-2=126.
12 Name five routing protocols that support VLSM.
Answer: Routing protocols that support VLSM include the following:
• RIP Version II
• OSPF
• IS-IS
• EIGRP
• BGP4
13 What is the destination port number used in a Telnet session?
Answer: The TCP port number is 23, and the source port is a random number
generated by the host device.
14 What TCP/IP services are common in today’s large IP networks?
Answer: TCP/IP has a number of applications or services in use:
• Address Resolution protocol (ARP)
• Reverse Address Resolution protocol (RARP)
• Dynamic Host Configuration Protocol (DHCP)
• Hot Standby Router Protocol (HSRP)
• Internet Control Message Protocol (ICMP)
• Telnet
• File transfer protocol (FTP)
• Trivial File Transfer Protocol (TFTP)
15 What IOS command displays the IP ARP table on a Cisco IOS router?
Answer: The IOS command is show ip arp. This command displays IP ARP entries
only. IOS command, show arp, displays all ARP entries for all protocols in use.
16 Cisco routers use what mechanism to determine the routing selection policy for remote
networks if more than one routing protocol is running?
Answer: Cisco IOS routers use administrative distance, which defines a set number
for every routing protocol in use. The lower the AD, the more trustworthy the
network. For example, a static route (AD is 1) is preferred to an OSPF (AD is 110)
discovered route. A static route pointing to a directly connected interface, for
example, via ethernet0, has an AD set to 0, the same as a directly connected interface
even though a static route is enabled.
17 What is the administrative distance for OSPF, RIP, and external EIGRP?
Answer: The AD for RIP is 120, 110 for OSPF, and 170 for external EIGRP (internal
EIGRP is 90).
18 Name five characteristics of distance vector routing protocols and provide two examples
of routing protocols classified as distance vector.
Answer: Distance vector characteristics and example protocols are as follows:
19 IP RIP runs over what protocol and port number when sending packets to neighboring
routers?
Answer: UDP port number 520
20 How many networks can be contained in an IP RIP update?
Answer: Up to 25 networks
21 Specify three main differences between RIPv1 and RIPv2?
Answer: RIPv1 does not support VLSM, authentication, or multicast updates.
RIPv2 supports VLSM, authentication, multicast updates, and unicast updates to
remote routers.
22 What is an EIGRP Feasible Successor?
Answer: An EIGRP Feasible Successor is a neighboring EIGRP Cisco router with a
lower AD.
23 What is the metric used by OSPF?
Answer: The metric used by OSPF is cost and is defined by the formula 108/
Bandwidth for a given interface. The cost to a remote path is the sum of all the costs
that a packet will transverse to reach the remote network.
24 If OSPF is configured for one area, what area assignment should be used?
Answer: Good OSPF design defines area 0, or the backbone, as the core area, and
area 0 should always be used. If the OSPF network resides in one area only,
theoretically, any area assignment is possible.
25 What LSA types are not sent in a total stubby area?
Answer: Totally stubby areas block LSA types 3, 4, and 5. Although similar to a stub
area, a totally stubby area blocks LSAs of type 3, as well. This solution is Cisco
proprietary and is used to further reduce a topological database. The only Link State
Advertisement (LSA) type permitted is a specific type 3 LSA advertising a default
router only.
26 What IOS command disables an interface from participating in the election of an OSPF
DR/BDR router?
Answer: To disable an interface on a Cisco router when electing a DR, the IOS
command is ip ospf priority 0. The router with the highest priority (range is between
0 and 255) will be elected the DR.
27 On an Ethernet broadcast network, a DR suddenly reboots. When the router recovers and
discovers neighboring OSPF routers, will it be the designated router once more?
Answer: Once the router fails, the Backup DR (BDR) assumes the functions of the
DR and another OSPF router (if it exists) is elected the BDR. After the failed router
recovers, neighboring OSPF hello packets will advise that a DR/BDR already exists
and there is no need to assume the functions of DR or BDR until another election
process is initiated.
28 What Layer 4 protocol does BGP use to guarantee routing updates, and what destination
port number is used?
Answer: BGP4 uses TCP and the destination port number is 179.
29 What are ISDN BRI and PRI?
Answer: ISDN can be supplied by a carrier in two main forms: Basic Rate Interface
(BRI) and Primary Rate Interface (PRI). An ISDN BRI consists of two 64-kbps
services (B channels) and one 16-kbps signaling channel (D channel). An ISDN PRI
consists of 23 B or 30 B channels and a 64-kbps D channel, depending on the country.
In North America and Japan, a PRI service consists of 23 B channels for a total bit
rate of up to 1.544 Mbps. In Asia and Australia, a PRI delivers 30 B-channels and
one 64-kbps D channel, delivering a total bit rate of 2.048 Mbps.
30 What are the three phases that occur in any PPP session?
Answer: The three phases that occur in any PPP session are
• Link establishment—Link Control Program (LCP) packets are sent to
configure and test the link.
• Authentication (optional)—After the link is established, authentication can be
used to ensure that link security is maintained.
• Network layers—In this phase, NCP packets determine which protocols will be
used across the PPP link. An interesting aspect of PPP is that each protocol (IP,
IPX, and so on) supported in this phase is documented in a separate RFC that
discusses how it operates over PPP.
31 Define what BECN and FECN mean in a Frame Relay network?
Answer: Forward explicit congestion notification (FECN)—Bit set by a Frame Relay
network device to inform DTE receiving the frame that congestion was experienced
in the path from source to destination. DTE receiving frames with the FECN bit set
can request that higher-level protocols take flow-control action, as appropriate.
Backward explicit congestion notification (BECN)—Bit set by a Frame Relay
network device in frames traveling in the opposite direction of frames encountering
a congested path. DTE receiving frames with the BECN bit set can request that
higher-level protocols take flow-control action, as appropriate.
32 Frame Relay DLCI values are used for what purpose?
Answer: The data-link connection identifier (DLCI) value specifies a PVC or SVC in
a Frame Relay network. DLCIs are locally significant. There are globally significant
DLCIs used for LMI communication between Frame Relay switches.
33 What is the IP address range used in IP multicast networks?
Answer: The range of networks is from 224.0.0.0 to 239.255.255.255.
34 What type of network environment typically uses an AS5300?
Answer: The AS5300, or universal Access Server (AS), is a versatile data communications
platform that provides the functions of an access server, router, and digital
modems in a single modular chassis. Internet Service Providers typically use AS5300
to allow clients to use ISDN or PSTN when accessing the Internet. The AS5300 also
supports voice communication.
1.Which layer of the OSI model is responsible for converting frames into bits and bits
into frames?
a. Physical
b. Network
c. Transport
d. LLC sublayer
e. Data link
The data link layer performs bit conversion to pass to the MAC sublayer.
2.Routing occurs at what layer of the OSI model?
a. Physical
b. Network
c. Transport
d. LLC sublayer
e. Data link
Routing is a Layer 3 (network layer) function.
3.Bridging occurs at what layer of the OSI model?
a. Physical
b. Network
c. Transport
d. Data link
The data link layer is where bridging is performed.
4.Which of the following is
not
part of the OSI model?
a. Network layer
b. Physical layer
c. Operational layer
d. Application layer
The operational layer is not one of the seven OSI layers. The OSI model layers are
physical, data link, network, transport, session, presentation, and application.
5.IP operates at what layer of the OSI model?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
e. Layer 5
f. Layer 6
g. Layer 7
IP operates at the network layer (Layer 3) and provides a path to a destination.
6.On which layer of the OSI model is data commonly referred to as segments?
a. Layer 4
b. Layer 3
c. Layer 2
d. Layer 1
The data on Layer 4 is commonly referred to as segments.
7.On which layer of the OSI model is data commonly referred to as packets?
a. Layer 1
b. Layer 2
c. Layer 4
d. Layer 3
The data on Layer 3 is commonly referred to as packets.
8.Which layer of the OSI model transmits raw bits?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
At Layer 1, the lowest layer of the OSI model, bits are transferred across the wire.
9.Which of the following protocols is
not
routable?
a. IP
b. IPX
c. NetBEUI
d. NetBIOS
NetBEUI is not a routed protocol and must be bridged.
10.Which of the following is
not a required step to enable FastEther Channel (FEC)?
a. Ensure that all ports share the same speed at 10 Mbps.
b. Ensure that all ports share the same parameter such as speed.
c. Ensure that all ports operate at 100 Mbps.
d. Only eight ports can be bundled into a logical link or trunk.
FEC uses full-duplex Fast Ethernet (100 Mbps) links.
11.How is FastEther Channel best defined?
a. A bundle of 10-Mbps ports on a switch
b. Another name for half duplex 100 Mbps
c. Not available on Cisco Catalyst switches
d. The ability to bundle 100 Mbps ports into a logical link
e. Only supported with Gigabit ports
The FastEther Channel feature bundles 100 Mbps Fast Ethernet ports into a logical
link between two devices, such as Catalyst switches.
12.On what OSI layer does bridging occur?
a. Layer 1
b. Layer 2
c. Layer 3
d. Both Layer 1 and 2
Bridging occurs at the data link layer (Layer 2) of the OSI model.
13.In spanning tree, what is a BPDU?
a. A break protocol data unit
b. A routable frame
c. A bridge protocol data unit
d. A frame sent out by end stations
BPDU is a bridge protocol data unit.
14.An incoming frame on a Layer 2 switch is received on port 10/1 on a Catalyst 5000. If the
destination address is known through port 10/2, what happens?
a. The frame is discarded.
b. The frame is sent via port 10/2.
c. The frame is broadcast to all ports on the switch.
d. The frame is sent back via 10/1.
e. None of the above.
The destination MAC address has already been discovered through port 10/2, so the
frame will only be sent to the known port or slot 10, port 2.
15.Which of the following are the four possible states of spanning tree?
a. Listening, learning, blocking, broadcasting
b. Listening, learning, blocking, connecting
c. Discovering, learning, blocking, connecting
d. Listening, learning, blocking, forwarding
The four states of spanning tree are listening, learning, blocking, and forwarding.
16.How many bits make up an IP address?
a. 64 bits
b. 48 bits
c. 32 bits
d. 24 bits
e. 8 bits
IP addresses for IPv4 are 32 bits in length.
17.Identify the broadcast address for the subnet 131.108.1.0/24.
a. 131.108.1.1
b. 131.108.1.254
c. 131.108.1.255
d. 131.108.1.2
e. More data required
131.108.1.0/24 is a Class B address with a Class C mask, and the all (all binary 1s)
broadcast address is 131.108.1.255 (11111111).
18.Convert the following address to binary:
131.1.1.1/24
a. 10000011.1.1.1
b. 10000011.00000010.1.1
c. 10000011.1.1.01010101
d. 10000011.1.1.11111111
131.108.1.1 in binary is 10000011.00000001.00000001.00000001 or 10000011.1.1.1
19.How many subnets are possible in VLSM if the Class C address 131.108.255.0 is used
with the subnet mask 255.255.255.252 in the fourth octet field?
a. None
b. 100
c. 255
d. 254
e. 253
f. 252
g. 64
h. 62
2
6
–2 = 64–2 = 62.
20.How many hosts are available when a /26 subnet mask is used?
a. 254
b. 62
c. 64
d. 126
2
6
–2 = 64–2 = 62.
21.How many hosts are available in a Class C or /24 network?
a. 255
b. 254
c. 253
d. 0
e. More data required
A Class C or /24 network has 2
8
–2 = 256–2 = 254 addresses available for host devices.
22.You require an IP network to support at most 62 hosts. What subnet mask will accomplish
this requirement?
a. 255.255.255.255
b. 255.255.255.252
c. 255.255.255.224
d. 255.255.255.192
e. 255.255.255.240
62 hosts require 62+2 = 64 addresses. This needs 6 bits borrowed from the subnet
mask. In binary, that number is 11000000.
23.Which of the following are multicast addresses? (Choose all that apply.)
a. 224.0.0.5
b. 224.0.0.6
c. 221.0.0.5
d. 192.1.1.1
e. 131.108.1.1
224.0.0.5 and 224.0.0.6 are multicast addresses.
24.Which of the following routing protocols does not support VLSM?
a. RIPv1
b. RIPv2
c. OSPF
d. EIGRP
e. BGP
RIP version I is classful and does not carry subnet masks in routing updates.
25.What is the source TCP port number when a Telnet session is created by a PC to a Cisco
router?
a. 23
b. Not a known variable
c. 21
d. 20
e. 69
The source TCP port is a random number; the destination port is 23.
26.What best describes the ARP process?
a. DNS resolution
b. Mapping an IP address to a MAC address
c. Mapping a next-hop address to outbound interface on a Cisco router
d. Both a and b
ARP maps an IP address to a MAC address.
27.If two Cisco routers are configured for HSRP and one router has a default priority of 100
and the other 99, which router assumes the role of active router?
a. The default priority cannot be 100.
b. The router with a higher priority.
c. The router with the lowest priority.
d. Neither router because Cisco routers do not support HSRP; only clients do.
The highest priority assumes the role of active router.
28.A Cisco router has the following route table:
R1#show ip route
131.108.0.0/16 is variably subnetted, 17 subnets, 2 masks
C 131.108.255.0/24 is directly connected, Serial0/0
C 131.108.250.0/24 is directly connected, Serial0/1
O 131.108.254.0/24 [110/391] via 131.108.255.6, 03:33:03, Serial0/1
[110/391] via 131.108.255.2, 03:33:03, Serial0/0
R 131.108.254.0/24 [120/1] via 131.108.255.6, 03:33:03, Serial0/1
[120/1] via 131.108.255.2, 03:33:03, Serial0/
What is the preferred path to 131.108.254.0/24? (Choose the best two answers.)
a. Via Serial 0/0
b. Via Serial 0/1
c. None
d. To null0
OSPF is chosen because of the lower administrative distance of 110 compared to
RIP’s 120. Also notice OSPF load balancing between Serial0/0 and Serial0/1. (The
written examination always advises you how many answers to select. Practice on the
CD provided.)
29.IP RIP runs over what TCP port number?
a. 23
b. 21
c. 69
d. 520
e. None of the above
IP RIP does not use TCP port numbers; it uses UDP.
30.IP RIP runs over what UDP port number?
a. 23
b. 21
c. 69
d. 520
UDP 520
31.An OSPF virtual link should .
a. Never be used
b. Allow nonpartitioned areas access to the backbone
c. Allow partitioned areas access to the backbone
d. Not be used in OSPF, but in ISDN
Virtual links allow access to areas not directly connected to the backbone or
partitioned areas.
32.What is the BGP version most widely used today?
a. 1
b. 2
c. 3
d. 4
e. 5
f. 6
BGP4.
33.What is the destination port number used in a Telnet session?
a. 23
b. 69
c. 21
d. 161
Telnet, an application layer protocol, uses destination port 23.
34.In what fields does the IP checksum calculate the checksum value?
a. Data only
b. Header and data
c. Header only
d. Not used in an IP packet
The IP checksum calculation only covers the IP header.
35.The TCP header checksum ensures integrity of what data in the TCP segment?
a. The data only.
b. The header only.
c. The data and header.
d. There are no TCP header checksums; IP covers the calculation.
The TCP checksum calculation covers the TCP header and data.
36.ISDN BRI channels are made up of what?
a. 1
64 kbps channel and one D channel at 64 kbps
b. 2
64 kbps channels and one D channel at 64 kbps
c. 2
64 kbps channels and one D channel at 16 kbps
d. 32
64 kbps channels and one D channel at 16 kbps
ISDN basic rate interface (BRI) is two 64-kbps data channels and one signaling
channel (D Channel at 16 Kb).
37.What services can ISDN carry?
a. Data only
b. Data and voice only
c. Voice and video
d. Data, voice, and video
ISDN supports data, video, and voice.
38.Place the following steps in the correct order for PPP callback, as specified in RFC 1570.
1. A PC user (client) connects to the Cisco access server.
2. The Cisco IOS Software validates callback rules for this user/line and disconnects the
caller for callback.
3. PPP authentication is performed.
4. Callback process is negotiated in the PPP link control protocol (LCP) phase.
5. The Cisco Access Server dials the client.
a. 1, 2, 3, 4, 5
b. 1, 3, 2, 5, 4
c. 1, 4, 5, 3, 2
d. 5, 4, 3, 2, 1
RFC 1570 dictates how PPP callback is to be followed. For more information, refer
to www.cis.ohio-state.edu/cgi-bin/rfc/rfc1570.html.
39.What hardware port is typically designed to connect a Cisco router for modem access?
a. The console port
b. The vty lines
c. The auxiliary port
d. The power switch
e. The Ethernet interface
The auxiliary port on Cisco routers can be used for modem access. The console port
can also be used but, typically, the Aux port is applied for remote access or dialup
access for network failures.
40.The AS5300 series router can support which of the following incoming connections?
a. Voice
b. Dialup users via PSTN
c. ISDN
d. All the above
The AS5300 series router can support both digital (ISDN) and analogue connections,
and also supports voice traffic.
Q&A
1What are the seven layers of the OSI model?
Answer: The seven layers of the OSI model are as follows:
•Application
•Presentation
•Session
•Transport
•Network
•Data link
•Physical
2What layer of the OSI model is responsible for ensuring that IP packets are routed from
one location to another?
Answer: The network layer is primarily responsible for routing IP packets from one
destination to another.
3What mechanism is used in Ethernet to guarantee packet delivery over the wire?
Answer: Carrier Sense Multiple Access/Collision Detection (CSMA/CD) is the
Ethernet mechanism used to ensure that when devices detect collisions, other devices
on the segment are sent a jam signal. CSMA/CD ensures that when collisions occur,
other devices (such as PCs or routers) back off (do not transmit) for a specified
period of time. When a device receives a jam signal, it will wait a random amount of
time to retransmit. This lowers the chance of another collision. All devices that detect
a jam signal can transmit up to 16 times before sending an error message to the
application layer.
4Name two physical characteristics of 10BaseT?
Answer: 10BaseT is an Ethernet physical layer standard that defines a maximum
length of 100 m and a network speed of 10 Mbps.
5What Catalyst command displays the bridging or CAM table on a Cisco 5000 series
switch?
Answer: show cam dynamic
6What are the possible states of spanning tree?
Answer: The possible states of spanning tree are as follows:
•Disabled—The port is not participating in spanning tree and is not active.
•Listening—The port has received data from the interface and will listen for
frames. In this state, the bridge only receives data and does not forward any
frames to the interface or to other ports.
•Learning—In this state, the bridge still discards incoming frames. The source
address associated with the port is added to the CAM table. BPDUs are sent and
received.
•Forwarding—The port is fully operational; frames are sent and received.
•Blocking—The port has been through the learning and listening states and,
because this particular port is a dual path to the root bridge, the port is blocked
to maintain a loop-free topology.
The order of spanning tree states is listening, then learning, and, finally, forwarding
or blocking. Typically, each state takes around 15 seconds on Cisco Catalyst switches.
7FastEther Channel (FEC) allows what to occur between Cisco Catalyst switches?
Answer: FEC is a Cisco method that bundles 100 MB/s fast Ethernet ports into a
logical link between Cisco Catalysts switches, such as the Catalyst 5000 or 6000
series switches.
Up to four ports can be bundled together to scale bandwidth up to 800 Mbps.
8What field in the IP packet guarantees data delivery?
Answer: The IP frame format has no settings that guarantee packet delivery, so IP
is termed connectionless. The error check is only performed on the IP header fields,
not the data in the packet.
9Name some examples of connection-orientated protocols used in TCP/IP networks.
Answer: Connection-orientated protocols include TCP, FTP, and Telnet.
10 Given the address, 131.108.1.56/24, what are the subnet and broadcast addresses? How
many hosts can reside on this network?
Answer: The subnet is 131.108.1.0 and the broadcast address is 131.108.1.255. The
number of hosts is defined by the formula 28-2=256-2=254.
11 How many hosts can reside when the subnet mask applied to the network 131.108.1.0 is
255.255.255.128 (or 131.108.1.0/25)?
Answer: The number of hosts is 27-2=128-2=126.
12 Name five routing protocols that support VLSM.
Answer: Routing protocols that support VLSM include the following:
• RIP Version II
• OSPF
• IS-IS
• EIGRP
• BGP4
13 What is the destination port number used in a Telnet session?
Answer: The TCP port number is 23, and the source port is a random number
generated by the host device.
14 What TCP/IP services are common in today’s large IP networks?
Answer: TCP/IP has a number of applications or services in use:
• Address Resolution protocol (ARP)
• Reverse Address Resolution protocol (RARP)
• Dynamic Host Configuration Protocol (DHCP)
• Hot Standby Router Protocol (HSRP)
• Internet Control Message Protocol (ICMP)
• Telnet
• File transfer protocol (FTP)
• Trivial File Transfer Protocol (TFTP)
15 What IOS command displays the IP ARP table on a Cisco IOS router?
Answer: The IOS command is show ip arp. This command displays IP ARP entries
only. IOS command, show arp, displays all ARP entries for all protocols in use.
16 Cisco routers use what mechanism to determine the routing selection policy for remote
networks if more than one routing protocol is running?
Answer: Cisco IOS routers use administrative distance, which defines a set number
for every routing protocol in use. The lower the AD, the more trustworthy the
network. For example, a static route (AD is 1) is preferred to an OSPF (AD is 110)
discovered route. A static route pointing to a directly connected interface, for
example, via ethernet0, has an AD set to 0, the same as a directly connected interface
even though a static route is enabled.
17 What is the administrative distance for OSPF, RIP, and external EIGRP?
Answer: The AD for RIP is 120, 110 for OSPF, and 170 for external EIGRP (internal
EIGRP is 90).
18 Name five characteristics of distance vector routing protocols and provide two examples
of routing protocols classified as distance vector.
Answer: Distance vector characteristics and example protocols are as follows:
19 IP RIP runs over what protocol and port number when sending packets to neighboring
routers?
Answer: UDP port number 520
20 How many networks can be contained in an IP RIP update?
Answer: Up to 25 networks
21 Specify three main differences between RIPv1 and RIPv2?
Answer: RIPv1 does not support VLSM, authentication, or multicast updates.
RIPv2 supports VLSM, authentication, multicast updates, and unicast updates to
remote routers.
22 What is an EIGRP Feasible Successor?
Answer: An EIGRP Feasible Successor is a neighboring EIGRP Cisco router with a
lower AD.
23 What is the metric used by OSPF?
Answer: The metric used by OSPF is cost and is defined by the formula 108/
Bandwidth for a given interface. The cost to a remote path is the sum of all the costs
that a packet will transverse to reach the remote network.
24 If OSPF is configured for one area, what area assignment should be used?
Answer: Good OSPF design defines area 0, or the backbone, as the core area, and
area 0 should always be used. If the OSPF network resides in one area only,
theoretically, any area assignment is possible.
25 What LSA types are not sent in a total stubby area?
Answer: Totally stubby areas block LSA types 3, 4, and 5. Although similar to a stub
area, a totally stubby area blocks LSAs of type 3, as well. This solution is Cisco
proprietary and is used to further reduce a topological database. The only Link State
Advertisement (LSA) type permitted is a specific type 3 LSA advertising a default
router only.
26 What IOS command disables an interface from participating in the election of an OSPF
DR/BDR router?
Answer: To disable an interface on a Cisco router when electing a DR, the IOS
command is ip ospf priority 0. The router with the highest priority (range is between
0 and 255) will be elected the DR.
27 On an Ethernet broadcast network, a DR suddenly reboots. When the router recovers and
discovers neighboring OSPF routers, will it be the designated router once more?
Answer: Once the router fails, the Backup DR (BDR) assumes the functions of the
DR and another OSPF router (if it exists) is elected the BDR. After the failed router
recovers, neighboring OSPF hello packets will advise that a DR/BDR already exists
and there is no need to assume the functions of DR or BDR until another election
process is initiated.
28 What Layer 4 protocol does BGP use to guarantee routing updates, and what destination
port number is used?
Answer: BGP4 uses TCP and the destination port number is 179.
29 What are ISDN BRI and PRI?
Answer: ISDN can be supplied by a carrier in two main forms: Basic Rate Interface
(BRI) and Primary Rate Interface (PRI). An ISDN BRI consists of two 64-kbps
services (B channels) and one 16-kbps signaling channel (D channel). An ISDN PRI
consists of 23 B or 30 B channels and a 64-kbps D channel, depending on the country.
In North America and Japan, a PRI service consists of 23 B channels for a total bit
rate of up to 1.544 Mbps. In Asia and Australia, a PRI delivers 30 B-channels and
one 64-kbps D channel, delivering a total bit rate of 2.048 Mbps.
30 What are the three phases that occur in any PPP session?
Answer: The three phases that occur in any PPP session are
• Link establishment—Link Control Program (LCP) packets are sent to
configure and test the link.
• Authentication (optional)—After the link is established, authentication can be
used to ensure that link security is maintained.
• Network layers—In this phase, NCP packets determine which protocols will be
used across the PPP link. An interesting aspect of PPP is that each protocol (IP,
IPX, and so on) supported in this phase is documented in a separate RFC that
discusses how it operates over PPP.
31 Define what BECN and FECN mean in a Frame Relay network?
Answer: Forward explicit congestion notification (FECN)—Bit set by a Frame Relay
network device to inform DTE receiving the frame that congestion was experienced
in the path from source to destination. DTE receiving frames with the FECN bit set
can request that higher-level protocols take flow-control action, as appropriate.
Backward explicit congestion notification (BECN)—Bit set by a Frame Relay
network device in frames traveling in the opposite direction of frames encountering
a congested path. DTE receiving frames with the BECN bit set can request that
higher-level protocols take flow-control action, as appropriate.
32 Frame Relay DLCI values are used for what purpose?
Answer: The data-link connection identifier (DLCI) value specifies a PVC or SVC in
a Frame Relay network. DLCIs are locally significant. There are globally significant
DLCIs used for LMI communication between Frame Relay switches.
33 What is the IP address range used in IP multicast networks?
Answer: The range of networks is from 224.0.0.0 to 239.255.255.255.
34 What type of network environment typically uses an AS5300?
Answer: The AS5300, or universal Access Server (AS), is a versatile data communications
platform that provides the functions of an access server, router, and digital
modems in a single modular chassis. Internet Service Providers typically use AS5300
to allow clients to use ISDN or PSTN when accessing the Internet. The AS5300 also
supports voice communication.
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