3. A technician is troubleshooting a network where it is suspected that a defective node in the
network path is causing packets to be dropped. The technician only has the IP address of the end
point device and does not have any details of the intermediate devices. What command can the
technician use to identify the faulty node?
The ping command is used to verify connectivity to a device,the
commands ipconfig /flushdns will cause the adapter to flush the DNS cache,
while ipconfig /**displaydns** will result in the display of the DNS information in the cache.
4. A user who is unable to connect to the file server contacts the help desk. The helpdesk technician
asks the user to ping the IP address of the default gateway that is configured on the workstation.
What is the purpose for this ping command?
A. To resolve the domain name of the file server to its IP address
B. To test that the host has the capability to reach hosts on other networks
C. To request that gateway forward the connection request to the file server
The ping command is used to test connectivity between hosts. The other options
describe tasks not performed by ping. Pinging the default gateway will test whether the host has
the capability to reach hosts on its own network and on other networks.
5. What is a function of the tracert command that differs from the ping command when they are used
on a workstation?
A. The tracert command shows the information of routers in the path.
B. The tracert command sends one ICMP message to each hop in the path.
C. The tracert command reaches the destination faster.
D. The tracert command is used to test the connectivity between two devices.
The tracert command sends three pings to each hop (router) in the path toward the
destination and displays the domain name and IP address of hops from their responses.
Because tracert uses the ping command, the travel time is the same as a
standalone ping command. The primary function of a standalone ping command is to test the
connectivity between two hosts.
6. Which ICMP message is used by the traceroute utility during the process of finding the path
between two end hosts?
Traceroute progressively increments the TTL (IPv4) or hop limit (IPv6) field (1, 2,
3, 4…) for sending sequence of ping commands. When a router senses that the TTL or hop limit
is 0, it will discard the packet and send a time exceeded message to the source of the traceroute.
The returned message contains the IP address of the router that discarded the packet. Hence the
traceroute utility learns the address of the router. This process continues and provides the trace
with the address of each hop (router) as the packets continue traveling through routers to reach
7. Which utility uses the Internet Control Messaging Protocol (ICMP)?
ICMP is used by IPv4 and IPv6 to provide for messages to be sent in the event of
certain errors and for informational purposes.
9. A network administrator is testing network connectivity by issuing the ping command on a router.
Which symbol will be displayed to indicate that a time expired during the wait for an ICMP echo
When the ping command is issued on a router, the most common indicators are as
o ! – indicates receipt of an ICMP echo reply message
o . – indicates a time expired while waiting for an ICMP echo reply message
o U – an ICMP message of unreachability was received
10. Which two things can be determined by using the ping command? (Choose two.)
A. The destination device is reachable through the network
B. The average time it takes a packet to reach the destination and for the response to return to the source
C. The IP address of the router nearest the destination device
D.The number of routers between the source and destination device
A ping command provides feedback on the time between when an echo request was
sent to a remote host and when the echo reply was received. This can be a measure of network
performance. A successful ping also indicates that the destination host was reachable through the
11. A user calls to report that a PC cannot access the internet. The network technician asks the user to
issue the command ping 127.0.0.1 in a command prompt window. The user reports that the result
is four positive replies. What conclusion can be drawn based on this connectivity test?
A. The PC can access the network. The problem exists beyond the local network.
B. The TCP/IP implementation is functional.
C. The IP address obtained from the DHCP server is correct.
D.The PC can access the Internet. However, the web browser may not work.
The ping 127.0.0.1 command is used to verify that the TCP/IP stack is functional. It
verifies the proper operation of the protocol stack from the network layer to physical layer,
without sending a signal on the media. That is, this test does not go beyond the PC itself. For
example, it does not detect whether a cable is connected to the PC or not.
12. Which command can be used to test connectivity between two devices using echo request and
echo reply messages?
Ping is used to test connectivity between end devices. It can be used with both IPv4
and IPv6. Ping uses the ICMP protocol which issues an echo request/echo reply.
The ipconfig command is used at the command line of a Windows computer to display
IP addressing information. Netstat is used to display the local routing table.
13. What field content is used by ICMPv6 to determine that a packet has expired?
ICMPv6 sends a Time Exceeded message if the router cannot forward an IPv6
packet because the packet expired. The router uses a hop limit field to determine if the packet has
expired, and does not have a TTL field.
14. Which protocol provides feedback from the destination host to the source host about errors in
The ICMP protocol operates at Layer 3 of the OSI model, which is the Internet
layer of the TCP/IP model. ICMP encapsulates the ping and traceroute commands.
15. A network administrator can successfully ping the server at www.cisco.com, but cannot ping the
company web server located at an ISP in another city. Which tool or command would help
identify the specific router where the packet was lost or delayed?
The traceroute command provides connectivity information about the path a packet
takes to reach the destination and about every router (hop) along the way. It also indicates how
long a packet takes to get from the source to each hop and back.
16. What message is sent by a host to check the uniqueness of an IPv6 address before using that
In IPv6, Duplicate Address Detection (DAD) is used in place of ARP. An IPv6 host
performs DAD by sending a neighbor solicitation (NS) message to its own IPv6 address to
ensure the uniqueness of the address prior to using it.