In this network, host TestKing1 is able to send data to Host TestKing2. How will Router TestKingD handle the data frame received from Host TestKing1?

The TestKing network is shown below:

A. Router TestKingD will strip off the source MAC address and replace it with the MAC
address on the forwarding Fast Ethernet interface
B. Router TestKingD will strip off the source IP address and replace it with the IP address
on the forwarding Fast Ethernet interface
C. Router TestKingD will strip off the destination MAC address and replace it with the
MAC address of Host TestKing2
D. Router TestKingD will strip off the destination IP address and replace it with the IP
address of Host B
E. Router TestKingD will forward the data frame out interface Fast Ethernet0/1
F. Router TestKingD will forward the data frame out interface FastEthernet0/2

Answer: A, C, F

Explanation:

Whereas switches can only examine and forward packets based on the contents of the
MAC header, routers can look further into the packet to discover the network for which a
packet is destined. Routers make forwarding decisions based on the packet's
network-layer header (such as an IPX header or IP header). These network-layer headers
contain source and destination network addresses.

Local devices address packets to the router's MAC address in the MAC header. After
receiving the packets, the router must perform the following steps:

1. Check the incoming packet for corruption, and remove the MAC header . The
router checks the packet for MAC-layer errors. The router then strips off the MAC header
and examines the network-layer header to determine what to do with the packet.

2. Examine the age of the packet. The router must ensure that the packet has not come
too far to be forwarded. For example, IPX headers contain a hop count. By default, 15
hops is the maximum number of hops (or routers) that a packet can cross. If a packet has
a hop count of 15, the router discards the packet.

IP headers contain a Time to Live (TTL) value. Unlike the IPX hop count, which
increments as the packet is forwarded through each router, the IP TTL value decrements
as the IP packet is forwarded through each router. If an IP packet has a TTL value of 1,
the router discards the packet. A router cannot decrement the TTL value to 1 and then
forward the packet.

3. Determine the route to the destination. Routers maintain a routing table that lists
available networks, the direction to the desired network (the outgoing interface number),
and the distance to those networks. After determining which direction to forward the
packet, the router must build a new header. (If you want to read the IP routing tables on a
Windows 95/98 workstation, type ROUTE PRINT in the DOS box.)

4. Build the new MAC header and forward the packet.Finally, the router builds a new MAC header for the packet. The MAC header includes
the router's MAC address and the final destination's MAC address or the MAC address of
the next router in the path.
Figure 5 shows the contents of a packet before and after it has been forwarded by a router.
Figure 5 also shows the contents of the router's routing tables.
Figure 5: Routers forward packets based on the network address.

You work as a network engineer at TestKing.com. The topology of the TestKing.com network is displayed in the exhibit. Host TestKing1 has established a connection with the HTTP server attached to interface E0 of the TestKingB router. Which of the following statements describe the information contained in protocol data units sent from host TestKing1 to this server?

A. The destination port number in a segment header will have a value of 80.
B. The destination port number in a segment header will have a unique value greater than
or equal to 1023.
C. The destination address of a frame will be the MAC address of the HTTP server
interface.
D. The destination address of a frame will be the MAC address of the E0 interface of the
TestKingA router.
E. The destination IP address of a packet will be the IP address of the E0 interface of the
TestKingA router.
F. The destination address of a packet will be the IP address of the HTTP-Server

Answer: A, D, F

Explanation:

HTTP uses TCP port 80, making choice A correct. The source port will be chosen
randomly, but not the destination TCP port. The destination IP address will be left
unchanged, and since HTTP server is on a remote network, the destination MAC address
will be the MAC address of the default gateway ( E0 on TestKingA).

Host TestKingA needs to communications with the e-mail server shown above. What address will be placed on the destination address field of the frame when it leaves host TestKingA?

A TestKing office's network topology is shown in the diagram below:

A. The MAC address of TestKingA
B. The MAC address of switch TestKing1
C. The MAC address of the E0 interface of the TestKing3 router.
D. The MAC address of the E1 interface of the TestKing3 router.
E. The MAC address of switch TestKing2
F. The MAC address of the email server

Answer: C

Explanation:

If the destination host is in the remote segment than the router will change the MAC
address of the source to its own. The inverse ARP protocol is by default on. Remember
that IP address is not changed after forwarding. The MAC address is changed after
crossing each broadcast domain.

Based on the diagram below, which destination addresses will Host A use to send data to Host B?

The TestKing network is shown below:

A. The IP address of TestKing1
B. The IP address of TestKingA Fa0/0
C. The IP address of Host B
D. The MAC address of TestKing1
E. The MAC address of TestKingA Fa0/0
F. The MAC address of Host B

Answer: C, E

Explanation:

When sending data from one host to another, destination information will be added to
every packet's header. The destination information will be the IP and MAC Address of
destination host. If the destination is found outside the subnet the MAC address of the
router is used. Note: The destination IP address will never change, unless NAT is
involved.

The partial frame shown below displays select header information as it arrives at the destination host. Of the following choices shown below, which one represents the correct header information in the responding frame returned to the remote host?

Refer to the following exhibit:

Answer: A

Based on the diagram shown below, what is the correct addressing for a frame and packet received by Host TestKingB from Host TestKingA?

Refer to the following exhibit:

A. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e8f.088a
Destination IP: 192.168.60.5
Source IP: 192.168.60.1
B. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e8f.088a
Destination IP: 192.168.60.5
Source IP: 192.168.24.5
C. Destination MAC: 0011.43da.2c98
Source MAC: 00b0.d0ef.5f6a
Destination IP: 192.168.60.5
Source IP: 192.168.24.5
D. Destination MAC: 0011.43da.2c98
Source MAC: 0070.0e97.af4e
Destination IP: 192.168.60.5
Source IP: 192.168.60.2
E. None of the above

Answer: B

Explanation:

When packets leave from the host, the packets contains the source MAC and IP of the
host address. The source and destination IP address will not change. Because the host
knows that the destination is on another subnet, it will forward the packet to the default
gateway device, so the destination MAC address will be of the default gateway, which is
the FA0/0 interface of router TestKing3.

TestKing uses EIGRP as the routing protocol. Based on the info shown above, what path will packets take from a host on the 192.168.10.192/26 network to a host on the LAN attached to routerTESTKING1?

The TestKing network is shown in the following exhibit:

A. The path of the packets will be TESTKING3 to TESTKING2 to TESTKING1
B. The path of the packets will be TESTKING3 to TESTKING1 to TESTKING2
C. The path of the packets will be both TESTKING3 to TESTKING2 to TESTKING1
AND TESTKING3 to TESTKING1
D. The path of the packets will be TESTKING3 to TESTKING1
E. None of the above

Answer: D

Explanation:

Based on the routing table of TestKing3, the best path to the TestKing1 LAN is shown on
the first routing entry (192.168.10.64). TestKing 3 will use the Serial 0/0 interface to
route traffic to this destination, with the next hop IP address of 192.168.10.9, which is the
network used between TestKing3 and TestKing1, making choice D correct. Note that
there is only one routing entry for this destination. If traffic were load balancing over both
paths, then both would be displayed in the routing table.

Host TestKingA pings Host TestKingB, which entry will be in the ARP cache of Host TestKingA to support this transmission?

Part of the TestKing network topology is shown below:

Entry exhibit:

A. A
B. B
C. C
D. D
E. E

Answer: C

What symbol represents a type of device that is connected to interface FastEthemet 0/23 of the 2960 switch Sw1-2960?

Refer to the graphic shown below:

A. Picture A
B. Picture B
C. Picture C
D. Picture D

Answer: D

Explanation:

Some of the common Cisco symbols are shown below:

Note: Choice B in this question represents an ATM switch, which is not pictured above.
From the output shown in this question, we can see that there a numerous different MAC
addresses associated with port Fa 0/23. This can only mean that a device with multiple
hosts attached to it is plugged into this port, such as a hub or another switch.

What could cause the symptoms?

The Testking network is shown below:

A technician is investigating a problem with the network shown above. These
symptoms have been observed:

1. All of the user hosts can access the Internet.
2. None of the user hosts can access the server in VLAN9
3. All of the hosts can ping each other.

A. Interface S0/0 on the router is down.
B. Interface Fa0/1 on the router is down.
C. Interface Fa0/5 on Testking3 is down.
D. Interface Fa0/4 on Testking3 is down.
E. Testking2 is turned off.
F. Trunking is not enabled on the link between Testking1 and Testking3.

Answer: D

Explanation:

Since all user hosts have access to internet, link to router has to be up. Therefore, router
interface (Fa0/1 - believe it is labeled incorrectly on diagram as Fa1/0) must be up. Since
all hosts can ping each other, but none can get to VLAN 9 which is through single
interface Fa0/4, this interface must be down.
Choice A: incorrect, S0/0 must be up if internet access available.
Choice B: incorrect, Fa0/1 must be up if internet access (through router) available.
Choice C: incorrect, would not prevent access to VLAN9 via other routes (i.e Fa0/7,
Fa0/9, Fa0/4)
Choice D: correct
Choice E: incorrect: TestKing2 must be up if internet access (through switch and then
router) available
Choice F: incorrect: Disabled trunking on link between TestKing1 and TestKing3 would
not prevent access to VLAN9 via other routes

The routers in this network are running RIPv2. Which addressing scheme would satisfy the needs of this network yet waste the fewest addresses?

A TestKing network is shown in the exhibit below:

A. Network 1: 192.168.10.0/26Network 2: 192.168.10.64/26Network 3:
192.168.10.128/26Serial link 1: 192.168.20.0/24Serial link 2: 192.168.30.0/24
B. Network 1: 192.168.10.0/26Network 2: 192.168.10.64/28Network 3:
192.168.10.80/29Serial link 1: 192.168.10.88/30Serial link 2: 192.168.10.96/30
C. Network 1: 192.168.10.0/26Network 2: 192.168.10.64/27Network 3:
192.168.10.96/28Serial link 1: 192.168.10.112/30Serial link 2: 192.168.10.116/30
D. Network 1: 192.168.10.0/27Network 2: 192.168.10.64/28Network 3:
192.168.10.96/29Serial link 1: 192.168.10.112/30Serial link 2: 192.168.10.116/30

Answer: C

Explanation:

Network 1

Required Number of hosts :50
When We use the 26 bits for Network : 11111111.11111111.11111111.11000000 so 62
usable host can be in one network. 50 host for now and remaining hosts address for
further growth.

Network 2

Required Number of Hosts: 20

When we use the 27 bits for Network: 11111111.11111111.1111111.11100000 so 30
usable hosts can be in one network.

Network 3

Required Number of Hosts: 10
When we use the 28 bits for Network: 11111111.11111111.11111111.11110000 so 14
usable hosts can be in one network.

Connection between TK1, TK2 and TK3 is WAN so when you use 30 bits network IP,
you will not lose any IP addresses from network since this subnet allows for only 2 host
addresses.

Which of the following four designs is to be preferred?

You work as a network technician at TestKing.com. You have been assigned the
task of designing a new TestKing internetwork. The main priority is to minimize the
link costs. TestKing.at the same time wants to ensure the branch offices with direct
connectity to the main site.

A. Design TestKingA
B. Design TestKingB
C. Design TestKingC
D. Design TestKingD

Answer: C

Explanation:

Every network looks for cost efficiency. Redundancy is often sacrificed on the altar of monthly
cost. Thus, the hub and spoke Frame Relay network design is one of the more common.
In this configuration, you pick a centralized location (most likely, your largest, most
connected office) as the "hub" of the network. All other locations are considered "spokes"
and have a single virtual circuit connection back to the hub.

The major advantage of this configuration is the cost. It offers the cheapest monthly price
tag, which cost-cutting corporations enjoy. The disadvantages are beginning to mount
against this design, however. The redundancy is sorely lacking. If a single router (the
central router) loses connectivity for any reason (if the router crashes, if a trenching
company cuts through the line), your entire WAN goes down. The other disadvantage of
this design is beginning to eclipse even redundancy. It is the disadvantage of tandem
switching. Any time the spoke offices need to reach each other, they must go through the
hub office.

Which of the following four designs would provide some redundancy and increase reliability for all four sites, but would cost less than a fully redundant topology?

You work as a network technician at TestKing.com. You have been assigned the
task of designing a new TestKing internetwork. The main priority is the achieve the
highest reliability available, however not at all costs. TestKing.com is willing to
spend more dollars to avoid downtime caused by link failure.

A. Design TestKingA
B. Design TestKingB
C. Design TestKingC
D. Design TestKingD

Answer: B

Explanation:

You can think of the partial mesh Frame Relay design as the compromise between
network administrators and cost-saving managers.

Which of the following four designs is to be preferred?

You work as a network technician at TestKing.com. You have been assigned the
task of designing a new TestKing internetwork. The main priority is to achieve the
highest reliability available. TestKing.com is willing to spend more dollars to avoid
downtime caused by link failure.

A. Design TestKingA
B. Design TestKingB
C. Design TestKingC
D. Design TestKingD

Answer: A

Explanation:

A network topology that is set up so that each device is directly connected to every other
device on the network. This connection method has built-in redundancy. If one link goes
down, the device will transmit via another link.

Example:
If the partial mesh design is a compromise between the network administrators and
managers, then the full mesh design implies that the network administrators won. This
design is every Cisco network administrator's picture of perfection over a Frame Relay
cloud. It gives every site a direct virtual circuit to every other site, as shown in Figure
This design gives maximum redundancy and minimum packet latency (latency describes
how long it takes a packet to reach each location).

You work as a network technician for TestKing and are responsible for this network. Based on the diagram shown above, how many collision domains are there?

 Part of the TestKing network is shown above:

A. Six
B. Fourteen
C. Four
D. Two
E. Three
F. One
G. Eight

Answer: D

The corporate head office of TestKing has a teleconferencing system that uses VOIP (voice over IP) technology. This system uses UDP as the transport for the data transmissions. If these UDP datagrams arrive at their destination out of sequence, what will happen?

A. UDP will send an ICMP Information Request to the source host.
B. UDP will pass the information in the datagrams up to the next OSI layer in the order
that they arrive.
C. UDP will drop the datagrams.
D. UDP will use the sequence numbers in the datagram headers to reassemble the data in
the correct order.
E. UDP will not acknowledge the datagrams and wait for a retransmission of the
datagrams.

Answer: B

Explanation:

VOIP systems utilize UDP because it is faster and uses less overhead. In addition, the
reliable transport mechanism used in TCP is useless to VOIP because if a packet gets
dropped and needs to be resent, it will be already too late.

UDP provides a service for applications to exchange messages. Unlike TCP, UDP is
connectionless and provides no reliability, no windowing, and no reordering of the
received data. However, UDP provides some functions of TCP , such as data transfer,
segmentation, and multiplexing using port numbers, and it does so with fewer bytes of
overhead and with less processing required. UDP data transfer differs from TCP data
transfer in that no reordering or recovery is accomplished. Applications that use UDP are
tolerant of lost data, or they have some application mechanism to recover data loss.

Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press,
ISBN 1-58720-094-5) Page 161.

TestKing is installing IP phones in a new office. The phones and office computers connect to the same device. To ensure maximum throughout for the phone data sessions, the company needs to make sure that the phone traffic is on a different network from that of the office computer data traffic. What is the best network device to which to directly connect the phones and computers and what technology should be implemented on this device?

A. VLAN
B. Subinterface
C. STP
D. Hub
E. Switch
F. Router
G. Wireless Access Point
H. VTP

Answer: A, E

Which Layer 4 protocol is used for a Telnet connection between two TestKing routers?

A. IP
B. ICMP
C. DNS
D. TCP
E. UDP
F. RTP

Answer: D

Explanation:

TCP is a reliable connection-oriented protocol. TCP uses acknowledgments, sequencing,
and flow control to ensure reliability. Telnet uses TCP port 23.

Which of the following are types of flow control?

A. Buffering
B. Cut-through
C. Windowing
D. Congestion avoidance
E. Load balancing

Answer: A, C, D

Explanation:

Data transmission flow control occurs at layer 4 with the help of buffering, windowing
and congestion avoidance.

Reference: CCNA Cisco Certified Network Associate Study Guide, 5th Edition, Todd
Lammle, chapter 1, page 17.

Which of the following services use TCP?

A. DHCP
B. SMTP
C. SNMP
D. FTP
E. HTTP
F. TFTP

Answer: B, D, E

Explanation:

TCP (Transmission Control Protocol) is a reliable mechanism for data delivery. SMTP,
FTP and HTTP services use TCP via ports 25, 20/21, and 80, respectively.

ICMP is often used in troubleshooting and verifying network. What statements are true regarding ICMP packets?

A. They acknowledge receipt of TCP segments.
B. They guarantee datagram delivery.
C. They can provide hosts with information about network problems.
D. They are encapsulated within IP datagrams.
E. They are encapsulated within UDP datagrams.
F. They are encapsulated within TCP datagrams.

Answer: C, D

Explanation:

ping may be used to find out whether the local machines are connected to the network or whether a remote site is reachable. This tool is a common network tool for determining the network connectivity which uses ICMP protocol instead of TCP/IP and UDP/IP. This protocol is usually associated with the network management tools which provide network information to network administrators, such as ping and traceroute (the later also uses the UDP/IP protocol).

ICMP is quite different from the TCP/IP and UDP/IP protocols. No source and destination ports are included in its packets. Therefore, usual packet-filtering rules for TCP/IP and UDP/IP are not applicable. Fortunately, a special "signature" known as the packet's Message type is included for denoting the purposes of the ICMP packet. Most commonly used message types are namely, 0, 3, 4, 5, 8, 11, and 12 which represent echo reply, destination unreachable, source quench, redirect, echo request, time exceeded, and parameter problem respectively.

In the ping service, after receiving the ICMP "echo request" packet from the source location, the destination

Incorrect Answers:

ICMP is an IP protocol so A and E are incorrect.
ICMP doesn't guarantee datagram delivery so B is wrong as well.

You have set up an Internet based FTP server, where people can upload and download files. In terms of the OSI model, what is the highest layer used during the FTP sessions.

A. Application
B. Presentation
C. Session
D. Transport
E. Internet
F. Data Link
G. Physical

Answer: A

Explanation:

The application layer is the highest layer (layer 7) of the OSI model, and is reserved for
end user applications. Since FTP is itself an application, layer 7 is the highest layer used.

Incorrect Answers:

B, C, D, E, F, G. In any given FTP session, all of these layers will be used at some point
but they are incorrect because the question asked for the highest layer used by FTP.

A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

A. Start a new session using UDP
B. Obtain a new IP address from the DHCP server
C. Use a different source port for the session
D. Decrease the sequence number
E. Decrease the window size

Answer: E

Explanation:

A TCP window the amount of outstanding (unacknowledged by the recipient) data a sender can send on a particular connection before it gets an acknowledgment back from the receiver that it has gotten some of it.

For example if a pair of hosts are talking over a TCP connection that has a TCP window size of 64 KB (kilobytes), the sender can only send 64 KB of data and then it must stop and wait for an acknowledgment from the receiver that some or all of the data has been received. If the receiver acknowledges that all the data has been received then the sender is free to send another 64 KB.

One way to improve the reliability of the TCP connection is to reduce the window size that the receiver needs to receive before sending an acknowledgement. However, this will reduce throughput as more segments and acknowledgements will need to be sent in order to transfer the same amount of data.

Acknowledgements, sequencing, and flow control are functions that are handled by which layer of the OSI model?

A. Layer 5
B. Layer 4
C. Layer 7
D. Layer 6
E. Layer 3
F. Layer 2
G. Layer 1

Answer: B

Which fields are included in the TCP header?

A. Source Port
B. Acknowledgement Number
C. Request Number
D. Destination Address
E. Window
F. Data

Answer: A, B, E

Explanation:

TCP header:

Source Port: 16 bits.
Destination Port: 16 bits.
Sequence Number: 32 bits.

The sequence number of the first data byte in this segment. If the SYN bit is set, the sequence number is the initial sequence number and the first data byte is initial sequence number + 1.

Acknowledgment Number: 32 bits.

If the ACK bit is set, this field contains the value of the next sequence number the sender of the segment is expecting to receive. Once a connection is established this is always sent.

Data Offset: 4 bits.
The number of 32-bit words in the TCP header. This indicates where the data begins. The
length of the TCP header is always a multiple of 32 bits.
Reserved: 3 bits.
Must be cleared to zero.
ECN, Explicit Congestion Notification: 3 bits.
Added in RFC 3168.
Control Bits: 6 bits.
Window: 16 bits, unsigned.
The number of data bytes beginning with the one indicated in the acknowledgment field
which the sender of this segment is willing to accept.
Checksum: 16 bits.
This is computed as the 16-bit one's complement of the one's complement sum of a
pseudo header of information from the IP header, the TCP header, and the data, padded as
needed with zero bytes at the end to make a multiple of two bytes.
Urgent Pointer: 16 bits, unsigned.
If the URG bit is set, this field points to the sequence number of the last byte in a
sequence of urgent data.
Options: 0 to 44 bytes.
Options occupy space at the end of the TCP header. All options are included in the
checksum. An option may begin on any byte boundary. The TCP header must be padded
with zeros to make the header length a multiple of 32 bits.
Data: Variable length.

Which of the protocols below use TCP at the transport layer?

A. TFTP
B. SMTP
C. SNMP
D. FTP
E. HTTP
F. HTTPS


Answer: B, D, E, F

Explanation:

SMTP (Simple Mail Transfer Profile for email), FTP (File Transfer Protocol), and
HTTP/HTTPS (Hyper Text Transfer Protocol for internet) all use TCP because of the
reliable delivery mechanism. SMTP uses TCP port 25, FTP uses TCP ports 20 and 21,
HTTP uses TCP port 80, and HTTPS uses TCP port 443.

Incorrect Answers:

A, C: SNMP and TFTP use UDP as the transport mechanism. Generally speaking,
protocols that use the keywords "trivial" or "simple" uses UDP, since connectionless, best
effort delivery mechanism usually suffice.

Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press,
ISBN 1-58720-094-5) Page 163.

As a CCNA candidate, you will be expected to know the OSI model very well. Which of the following are associated with the application layer (layer 7) of the OSI model?

A. TCP
B. Telnet
C. FTP
D. Ping
E. IP
F. UDP

Answer: B, C

Explanation:

The application layer is the top layer of the OSI model and is used to describe the end
user applications that can be used over a network.

Layer Name Examples

Application (layer 7) Telnet, HTTP, FTP, WWW browsers, NFS, SMTP gateways,SNMP

Incorrect Answers:

A. TCP resides at layer 4.
D. ARP is a function of the data link layer, which is layer 2.
E. IP is used at layer 3 (network layer).
Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press,
ISBN 1-58720-094-5) Page 34.

Which protocol below uses TCP port 443 at layer 4?

A. HTML
B. HTTPS
C. TFTP
D. Telnet
E. SMTP
F. None of the above

Answer: B

Explanation:

HTTPS is the secured version of the HTTP application, which normally uses 128 bit SSL
encryption to secure the information sent and received on a web page. An example is a
banking web site, or a trustworthy shopping web site that takes credit card information. It
is an application layer protocol which uses TCP port 443.

Incorrect Answers:

A. HTML is not a protocol.
C. TFTP uses UDP port 69.
D. Telnet uses TCP port 23.
E. SMTP uses TCP port 25.

You unsuccessfully try to ping the Internet from a PC host on the LAN. During the troubleshooting process, you enter the "show ip nat translations" command but the output is blank. What is the most likely cause of the problem?

A. The keyword overload is missing from the command.
B. The NAT pool must be defined first.
C. An access list must be defined to create static NAT translations.
D. The interfaces must be configured for NAT.
E. None of the above

Answer: D

Explanation:

In order to successfully configure a static NAT translation, the interfaces must be
configured for NAT, in addition to the global NAT command that was entered. The router
interface that lies on the inside part of the network must be defined using the "ip nat
inside" command. Similarly, the WAN interface that is being used for the Internet
connection must be defined using the "ip nat outside" command.

Incorrect Answers:

A. In order to make an internal server reachable from the Internet, a static one to one
NAT entry must be configured for the server. The keyword "overload" is used to
configure many to one NAT, or PAT.
B, C. This need not be done in order to create a static NAT entry. These steps are
typically done in setting up NAT so that inside LAN users can access the Internet via
NAT.

When files are transferred between a host and an FTP server, the data is divided into smaller pieces for transmission. As these pieces arrive at the destination host, they must be reassembled to reconstruct the original file. What provides for the reassembly of these pieces into the correct order?

A. The sequence number in the TCP header
B. The Start Frame Delimiter in the 802.3 Preamble
C. The TTL in the IP header
D. The acknowledgement number in the segment header
E. The frame check sequence in the Ethernet frame trailer

Answer: A

Explanation:

The Transport layer can provide reliable networking via acknowledgments, sequencing, and flow control.Acknowledgments Delivered segments are acknowledged to the sender. If they are not acknowledged, the sender will retransmit.Sequencing Data segments are sequenced into their original order when they arrive at the destination.

Flow Control Provides buffer controls that prevent packet flooding to the destination host. Buffers store bursts of data for processing when the transmission is complete.

Layer 4 protocols include the following:
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
Sequenced Packet Exchange (SPX)A reliable communications protocol created by Novell
NetWare

Which of the following correctly describe steps in the OSI data encapsulation process?

A. The presentation layer translates bits into voltages for transmission across the physical
link.
B. The transport layer divides a data stream into segments and adds reliability and flow
control information.
C. Packets are created when the network layer adds Layer 3 addresses and control
information to a segment.
D. The data link layer adds physical source and destination addresses and an FCS to the
segment.
E. Packets are created when the network layer encapsulates a frame with source and
destination host addresses and protocol-related control information.

Answer: B, C

Explanation:

The Transport Layer:

You can think of the transport layer of the OSI model as a boundary between the upper
and lower protocols. The transport layer provides a data transport service that shields the
upper layers from transport implementation issues such as the reliability of a connection.

The transport layer provides mechanisms for:

• Segmenting upper layer applications
• The establishment, maintenance, and orderly termination of virtual circuits
• Information flow control and reliability via TCP
• Transport fault detection and recovery.

The Network Layer:

Layer three of the OSI model is the network layer.

1. The network layer creates and sends packs from source network to destination network.
2. It provides consistent end-to-end packet delivery services and control information.
3. It creates and uses layer3 addresses for use in path determination and to forward packets.

Which OSI layer header contains the address of a destination host that is on another network?

A. Application
B. Presentation
C. Session
D. Transport
E. Network
F. Data link
G. Physical

Answer: E

Explanation:

Only network address contains this information. To transmit the packets the sender uses network address and datalink address. But the layer 2 address represents just the address of the next hop device on the way to the sender. It is changed on each hop. Network address remains the same.

Which OSI layer is associated with the following: The acknowledgement of transmissions, sequencing, and flow control across a network?

A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 5
E. Layer 6
F. Layer 7

Answer: C

Explanation:

The Transport layer (Layer 4) defines several functions, including the choice of protocols. The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols. Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included.

Examples include: TCP, UDP, and SPX.

Which layer of the OSI reference model is responsible for ensuring reliable end-to-end delivery of data?

A. Application
B. Presentation
C. Session
D. Transport
E. Network
F. Data-Link

Answer: D

Explanation:

A key function of the transport layer is to provide connection services for the protocoland applications that run at the levels above it. These can be categorized as either connection-oriented services or connectionless services. Some protocol suites, such as TCP/IP, provide both a connection-oriented and a connectionless transport layer protocol, to suit the needs of different applications.

The transport layer is also the place in the layer stack where functions are normally included to add features to end-to-end data transport. Where network layer protocols are normally concerned with just "best effort" communications, where delivery is not guaranteed. Transport layer protocols are given intelligence in the form of algorithms that ensure that reliable and efficient communication between devices takes place. This encompasses several related jobs, including lost transmission detection and handling, and managing the rate at which data is sent to ensure that the receiving device is not overwhelmed.

Transmission quality, meaning ensuring that transmissions are received as sent, is so important that some networking references define the transport layer on the basis of reliability and flow-control functions. However, not all transport layer protocols provide these services. Just as a protocol suite may have a connection-oriented and a connectionless transport layer protocol, it may also have one that provides reliability and data management services, and one that does not. Again, this is the case with TCP/IP: there is one main transport layer protocol; TCP, that includes reliability and flow control features, and a second, UDP, that doesn't.

A host computer has been correctly configured with a static IP address, but the default gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error?

A. Layer 1
B. Layer 2
C. Layer 3
D. Layer 4
E. Layer 5
F. Layer 6
E. Layer 7

Answer: C

Explanation:

IP Addressing and IP routing resides on the OSI Network layer, which is layer 3.

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You download a file from an FTP site on the Internet. What is the highest layer in the OSI model used in this FTP operation?

A. Application
B. Presentation
C. Session
D. Transport
E. Internet
F. Data Link
G. Physical

Answer: A

Explanation:

Layer 7 is the application layer, which is the highest layer in the OSI model. This layer
describes the use of end user applications, such as opening movie files (avi, mpeg, etc)
used Microsoft Office applications, using WWW browsers, using Telnet, and using FTP.

While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out."

At which OSI layer is this problem associated with?

A. The data link layer
B. The application layer
C. The access layer
D. The session layer
E. The network layer

Answer: E

Explanation:

TCP/IP includes ICMP, a protocol designed to help manage and control the operation of a
TCP/IP network. The ICMP protocol provides a wide variety of information about a
network's health and operational status. Control message is the most descriptive part of a
name. ICMP helps control and manage IP's work and therefore is considered part of
TCP/IP's network layer.

Reference:
CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press, ISBN
1-58720-083-X) page 277.

As a CCNA candidate, you must know the various layers of the OSI model. At which layers of the OSI Model do Wide Area Networks operate in? (Choose two)

A. Physical Layer
B. Datalink Layer
C. Network Layer
D. Session Layer
E. Transport Layer
F. Presentation Layer
G. Application Layer

Answer: A, B

Explanation:

A WAN is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower two layers of the OSI reference model: the physical layer and the data link layer as shown below.
                                           OSI Layers                            WAN Specifications

Note: Occasionally WAN's would also be considered to operate at layer 3, but since this
question asked for only 2 chopices layers 1 and 2 are better choices.

CDP is running between two TestKing devices. What information is supplied by CDP? (Select three)

A. Device Identifiers
B. Capabilities list
C. Platform
D. Route identifier
E. Neighbor traffic data

Answer: A, B, C

Explanation:

CDP is a Cisco Proprietary Protocol; to support forwarding CDP Messages over an interface, that interface must support SNAP headers. Any LAN interface, HDLC, Frame Relay, and ATM all support CDP. The Router or switch can discover layer 3 addressing details of nighboring routers - without even configuring that layer 3 Protocol - because CDP is not dependent on any particular Layer 3 protocol.

CDP Discovers several useful details from neighboring device:

• Device Identifier - Typically the host name
• Address List - Network and data link addresses
• Port Identifier - Text that identifies that port, which is another name for an interface
• Capabilities List - Information on what the device does - for instance, a router or switch
• Platform - The model and OS level running in the device

CDP is being used throughout the TestKing network. What are two reasons why the TestKing network administrator would use CDP? (Choose two)

A. To determine the status of network services on a remote device
B. To obtain the IP Address of a connected device in order to telnet to the device
C. To verify the type of cable interconnecting two devices
D. To verify Layer 2 connectivity between two devices when Layer 3 fails
E. To obtain VLAN information from directly connected swticehs
F. To determine the status of the routing protocols between directly connected routers
G. To support automatic network failover during outages

Answer: B, D

The TestKing network administrator needs to determine what LAN devices to install on the TestKing network. What are two advantages of using Layer 2 Ethernet switches over hubs? (Choose two)

A. Allowing simultaneous frame transmissions
B. Increasing the size of broadcast domains
C. Increasing the maximum length of UTP cabling between devices
D. Filtering frames based on MAC addresses
E. Decreasing the number of collision domains

Answer: A, D

Explanation:

A: A half duplex connection is where only one device can send or receive at a time. A full
duplex connection is where both devices can send and receive at the same time.
Thus, if you have a 100Mb half-duplex connection, only sending at 100Mb OR receiving
at 100Mb can happen at the same time. If you have a 100Mb full duplex connection, you
can effectively get 200Mb out of the link because you could be sending 100Mb and
receiving 100Mb at the same time.

D: Switches are capable of filtering frames based on any Layer 2 fields. For example, a
switch can be programmed to reject (not forward) all frames sourced from a particular
network. Because link layer information often includes a reference to an upper-layer
protocol, switches usually can filter on this parameter. Furthermore, filters can be helpful
in dealing with unnecessary broadcast and multicast packets.

As a network administrator, you will need to decide on the appropriate network devices to use. Which of the following correctly describes the roles of devices in a WAN? (Choose three)

A. A CSU/DSU terminates a digital local loop.
B. A router is commonly considered a DCE device.
C. A modem terminates an analog local loop.
D. A router is commonly considered a DTE device.
E. A modem terminates a digital local loop.
F. A CSU/DSU terminates an analog local loop.
G. A modem is used to terminate a T1

Answer: A, C, D

Both bridges are switches are being used throughout the TestKing LAN. Which of the following statements are true regarding bridges and switches in this network? (Choose 3)

A. Switches are primarily software based while bridges are hardware based.
B. Switches usually have a higher number of ports than most bridges.
C. Bridges are frequently faster than switches.
D. Bridges define broadcast domains while switches define collision domains.
E. Both bridges and switches forward Layer 2 broadcasts.
F. Both bridges and switches make forwarding decisions based on Layer 2 addresses.

Answer: B, E, F

Cisco is the leader in the router market space. What basic functions do their routers perform in a network? (Choose two)

A. The microsegmentation of broadcast domains
B. Path selection
C. Packet switching
D. Bridging between LAN segments
E. Access layer security
F. VLAN membership assignment
G. Application optimization

Answer: B, C

Explanation:

The primary functions of a router are: Packet Switching and Path Selection. It is the
routers job to determine the best method for delivering the data, and switching that data
as quickly as possible.

The LAN needs are expanding at the Testking corporate office, which is quickly growing. You are instructed to enlarge the area covered by a single LAN segment on the TestKing network. Which of the following are layer 1 devices that you can use? (Choose all that apply.)

A. A switch
B. A router
C. A network adapter card
D. A hub
E. A repeater

Answer: D, E

Explanation:

A hub simply repeats the electrical signal and makes no attempt to interpret the electrical
signal (layer 1) as a LAN frame (Layer 2). So, a hub actually performs OSI layer 1
functions, repeating an electrical signal, whereas a switch performs OSI layer 2 functions,
actually interpreting Ethernet header information, particularly addresses, to make
forwarding decisions. Hubs can be used to increase the number of stations that can be
supported on a LAN.

Because the repeater does not interpret what the bits mean, but does examine and
generate electrical signals, a repeater is considered to operate at Layer 1. Repeaters can be
used to physically extend the LAN to greater distances.

Which of the following correctly describe the various functions and virtues of a router? (Select all valid answer choices)

A. Packet switching
B. Collision prevention on a LAN segment.
C. Packet filtering
D. Broadcast domain enlargement
E. Broadcast forwarding
F. Internetwork communication
G. None of the above

Answer: A, C, F

Explanation:

The main function of a router is to connect different, separated networks together. In
doing so, switching packets from one network to another is a primary function, along
with providing for communication between networks. As an additional feature, routers
are capable of providing filtering on a network address and application port level, so
choice C is also correct.

Incorrect Answers:

B. Routers can indeed be used to segment a network separate a collision domain, since
routers do not forward LAN broadcasts and multicasts to other interfaces. However,
routers alone can not prevent all collisions from occurring on any given LAN segment.
D. Routers actually segment LANs into smaller broadcast domains.
E. Routers do not forward broadcast and multicast traffic out the additional interfaces by
default. Unless bridging or IP helpers are configured on the router, LAN broadcasts are
blocked at the router level.

When comparing and contrasting the similarities and differences between bridges and switches, which of the following are valid statements? Choose all the valid answer choices)

A. Bridges are faster than switches because they have fewer ports.
B. A switch is a multiport bridge,
C. Bridges and switches learn MAC addresses by examining the source MAC address of
each frame received.
D. A bridge will forward a broadcast but a switch will not.
E. Bridges and switches increase the size of a collision domain.
F. None of the above statements are true.

Answer: B, C

Explanation:

Both bridges and switches build the bridge table by listening to incoming frames and
examining the source MAC address in the frame.
Switches are multiport bridges that allow you to create multiple broadcast domains. Each
broadcast domain is like a distinct virtual bridge within a switch.

Incorrect Answers:

A. Switches are generally faster than bridges. Bridges also do not necessarily have fewer
ports than switches.
D. Both bridges and switches will forward broadcast and multicast traffic, assuming that
the traffic remains in the same VLAN.
E. The use of VLANs in a switch can decrease the size of the collision domain, by
creating additional, smaller collision domains.

Which one of the following characteristics is true regarding the use of hubs and switches?

A. Hubs can have their ports be configured with VLANs
B. Using hubs is costly with regard to bandwidth availability.
C. Switches can not forward broadcasts.
D. Switches are more efficient than hubs in processing frames.
E. Switches increase the number of collision domains in the network.

Answer: E

Explanation:

Switches increases the number of collisions domains in the network. Switches that
are configured with VLANs will reduce the size of the collision domains by
increasing the number of collision domains in a network, but making them smaller
than that of one big, flat network.

Incorrect Answers:

A. Switches are capable of VLAN configurations, but hubs are not.
B. Hubs are generally the least costly method possible to connect multiple devices
together in a network.
C. Switches forward broadcasts and multicasts, by default, to all ports within the same
VLAN. Only routers block all broadcast traffic by default.
D. Switches and hubs can be equally efficient in processing frames, in theory. In practice,
switches are generally more efficient as they usually have more CPU and memory
allocated to them, and are generally much more expensive than a simple hub.

Both switches and hubs are being utilized within the TestKing network. Which of the following is true regarding the use of switches and hubs for network connectivity in this network?

A. Switches take less time to process frames than hubs take
B. Hubs can filter frames
C. Switches do not forward broadcasts
D. Switches increase the number of collision domains in the network
E. Using hubs can increase the amount of bandwidth available to hosts
F. None of the above

Answer: D