Networking Devices and Initial Configuration

Which technology provides a solution to IPv4 address depletion by allowing multiple devices to share one public IP address?

NAT

What are two potential network problems that can result from ARP operation? (Choose two.)

Network attackers could manipulate MAC address and IP address mappings in ARP messages with the intent of intercepting network traffic. Large numbers of ARP request broadcasts could cause the host MAC address table to overflow and prevent the host from communicating on the network.

Which of the following best describes DHCP?

DHCP automates the assignment of IP addresses, subnet masks, gateways, and other IPv4 networking parameters.

Which DHCP IPv4 message contains the following information? Destination address: 255.255.255.255 Client IPv4 address: 0.0.0.0 Default gateway address: 0.0.0.0 Subnet mask: 0.0.0.0

DHCPDISCOVER

dhcp operation order

DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPNAK

Which three are transport layer responsibilities? (Choose three.)

conversation multiplexing, segmenting data and reassembling segments, tracking individual conversations

What is the order of encapsulation for the protocol data units passing from the user application down the stack?

data, segments, packets, frames, bits

session termination

fin, ack, fin, ack

switch(config)# hostname MainOiffice

an argument or value

top level domains examples

.com - a business or industry .org - a non-profit organization .au - Australia .co - Colombia

A user issues a ping 198.51.100.5 command and receives a response that includes a code of 3. What does this code represent?

0 : net unreachable 1 : host unreachable 2 : protocol unreachable 3 : port unreachable

Binary to dedcimal

128-64-32-16-8-4-2-1

DNS message format

A - An end device IPv4 address NS - An authoritative name server AAAA - An end device IPv6 address (pronounced quad-A) MX - A mail exchange record

What IPv4-related DNS record type is used by a DNS server in response to a host requesting for a web server address via the URL?

A DNS server uses an A record type for an IPv4 end device address.

What statement describes the function of the Address Resolution Protocol?

ARP is used to discover the MAC address of any host on the local network.

What is the protocol that is used to discover a physical address from a known logical address and what message type does it use?

ARP, broadcast

Hierarchical Network Design

Access, Distribution and Core

udp

Application dependent for error correction, Efficient delivery, Less overhead

What is a characteristic of a TCP server process?

Each application process running on the server is configured to use a port number, either by default or manually, by a system administrator. An individual server cannot have two services assigned to the same port number within the same transport layer services. A host running a web server application and a file transfer application cannot have both configured to use the same server port. There can be many ports open simultaneously on a server, one for each active server application.

Which two flags in the Layer 4 PDU header are set by a client and server to terminate a TCP conversation? (Choose two.)

FIN, ACK

Which forwarding action does a switch take when the destination MAC address of an Ethernet frame is an unknown unicast?

If the destination MAC address is a unicast address, the switch will look for a match between the destination MAC address of the frame and an entry in its MAC address table:

What is the aim of an ARP spoofing attack?

In an ARP spoofing attack, a malicious host intercepts ARP requests and replies to them so that network hosts will map an IP address to the MAC address of the malicious host.

Which TCP header statement is true?

It consists of 10 fields in a 20-byte header

Which statement describes a characteristic of the network layer in the OSI model?

It manages the data transport between the processes running on each host.

Four primary cloud models

Public clouds, Private clouds, Hybrid clouds, Community clouds

Copy running-config startup-config

R1#

Service password-encryption

R1(config)#

Ip address 192.168.4.4 255.255.255.0

R1(config-if)#

Login

R1(config-line)#

ARP is stored in

RAM

What action does the ARP process take when a host needs to build a frame, but the ARP cache does not contain an address mapping?

The ARP process sends out an ARP request to the Ethernet broadcast address to discover the MAC address of the destination device.

A user reports that the corporate web server cannot be accessed. A technician verifies that the web server can be accessed by its IP address. What are two possible causes of the problem? (Choose two.)

The DNS server address is misconfigured on the workstation. The web server information is misconfigured on the DNS server.

How does the network layer use the MTU value?

The MTU is passed to the network layer by the data link layer.

What field is used by the destination host to reassemble segments into the original order?

The sequence number field is used by the destination host to reassemble segments into the original order.

Which UDP datagram reassembly statement is true?

UDP reassembles the data in the order that it was received.

show arp in windows

arp -a

arp requests are

broadcasts

displays all of the cached DNS entries.

ipconfig /displaydns

Hexadecimal Number System

ipv6

What is a characteristic of the UDP protocol?

low overhead

Which two tasks can be performed by a local DNS server? (Choose two.)

mapping name-to-IP addresses for internal hosts forwarding name resolution requests between servers

packets

multiple message blocks

list the protocols in use, the local address and port numbers, the foreign address and port numbers, and the connection state.

netstat, netstat -n (display IP addresses and port numbers in their numerical form.)

Which Cisco IOS mode displays a prompt of Router#?

privileged EXEC mode

A network administrator establishes a connection to a switch via SSH. What characteristic uniquely describes the SSH connection?

remote access to a switch where data is encrypted during the session

hierarchy of domains

root level domain, top-level domain, second level domain (cisco.com, ftp.cisco.com or mail.cisco.com)

Which three fields are used in a UDP segment header? (Choose three.)

source, port, dest port, length, and checksumfield

packet switching

splits traffic into packets that are routed over a shared network

To save time, IOS commands may be partially entered and then completed by typing which key or key combination?

tab

Is connection-oriented, Uses acknowledgments, has a large header

tcp

ARP table is cached

temporarily

LLC vs mac

the LLC sublayer provides a logical connection and reliable communication between devices on a network, while the MAC sublayer governs access to the shared media and controls the transmission of data over it.

Which characteristic of the network layer in the OSI model allows carrying packets for multiple types of communications among many hosts?

the ability to operate without regard to the data that is carried in each packet

QoS

the primary mechanism, for managing congestion and ensuring reliable delivery of content (data, voice, and video), prioritize time-sensitive traffic. (type, not content of traffic, is important). managed by router.

Which ICMPv6 message is sent when the IPv6 hop limit field of a packet is decremented to zero and the packet cannot be forwarded?

time exceeded

An administrator uses the Ctrl-Shift-6 key combination on a switch after issuing the ping command. What is the purpose of using these keystrokes?

to interrupt the ping process or tacert

DNS

1. The user types an FQDN into a browser application Address field. 2. A DNS query is sent to the designated DNS server for the client computer. 3. The DNS server matches the FQDN with its IP address. 4. The DNS query response is sent back to the client with the IP address for the FQDN. 5. The client computer uses the IP address to make requests of the server.

Ethernet frame size

64 bytes to expected maximum 1518 bytes

What are two problems that can be caused by a large number of ARP request and reply messages?

ARP requests are sent as broadcasts: (1) All nodes will receive them, and they will be processed by software, interrupting the CPU. (2) The switch forwards (floods) Layer 2 broadcasts to all ports. A switch does not change its MAC table based on ARP request or reply messages. The switch populates the MAC table using the source MAC address of all frames. The ARP payload is very small and does not overload the switch.

Which three statements describe a DHCP Discover message? (Choose three.)

All hosts receive the message, but only a DHCP server replies. The destination IP address is 255.255.255.255. The message comes from a client seeking an IP address.

What are two features of protocols used within the TCP/IP protocol stack? (Choose two.)

Application programmers make decisions about which protocols to use to transport the data to and from their applications based on whether the application can tolerate any lost data. Live streaming and voice transmissions can use UDP because if a few data packets are lost, the quality of the video and audio is not seriously impacted. TCP is used when all data must be complete and accurate.

Which two fields are the same in a TCP and UDP header? (Choose two.)

Both TCP and UDP headers include a source and destination port number fields.

Access

Cisco 2960-XR

Distribution

Cisco C9300 Series

Core

Cisco Catalyst 9600

What does R1 use as the MAC address of the destination when constructing the frame that will go from R1 to Server B?

Communication inside a local network uses Address Resolution Protocol to obtain a MAC address from a known IPv4 address. A MAC address is needed to construct the frame in which the packet is encapsulated. If the destination MAC address that corresponds to the IPv4 address is not in the ARP cache, R1 sends an ARP request.

network security

Confidentiality - authorization Integrity - information is not altered in transmission Availability - timely and reliable

4 Basic characteristics that network architects must address to meet user expectations.

Fault Tolerance Scalability Quality of Service (QoS) Security

Which value, that is contained in an IPv4 header field, is decremented by each router that receives a packet?

Fragment Offset

When configuring SSH on a router to implement secure network management, a network engineer has issued the login local and transport input ssh line vty commands. What three additional configuration actions have to be performed to complete the SSH configuration? (Choose three.)

Generate the asymmetric RSA keys. Configure the correct IP domain name. Create a valid local username and password database.

Network congestion has resulted in the source learning of the loss of TCP segments that were sent to the destination. What is one way that the TCP protocol addresses this?

If the source determines that the TCP segments are either not being acknowledged or are not acknowledged in a timely manner, then it can reduce the number of bytes it sends before receiving an acknowledgment. This does not involve changing the window in the segment header. The source does not decrease the window that is sent in the segment header. The window in the segment header is adjusted by the destination host when it is receiving data faster than it can process it, not when network congestion is encountered.

Which UDP header statement is true?

It consists of 4 fields in an 8-byte header.

What does the letter C mean next to an entry in the output of the show ip route command?

It identifies a network that is directly connected to the router.

Ip Address is considered?

Logical

Why is UDP desirable for protocols that make a simple request and reply transactions?

Low overhead

Retransmission

Method of managing segments of data loss

Why would you activate more than one NIC on a PC?

Multiple NICs can be used if more than one path is needed for the PC. One example of this would be if the PC is being used as a proxy server.

Logical Address has two parts

Network, Host

Acknowledgmentwindow size

Number of bytes a destination device can accept and process at one time

Which statement describes the treatment of ARP requests on the local link?

One of the negative issues with ARP requests is that they are sent as a broadcast. This means all devices on the local link must receive and process the request.

Acknowledgment

Received by a sender before transmitting more segments in a session

Fault Tolerance

Redundancy - multiple paths

Refer to the exhibit. Host A is trying to resolve the name www.internal.cisco.com to an IP address. When the name resolution request is received by a root DNS server, which server will be included in the response for further resolution?

Root DNS servers only carry records for top-level domains (like .com or .org). If a host requests resolution from a root DNS server for the domain www.cisco.com, for example, the root DNS server would refer the client to the DNS server responsible for the .com domain. This DNS server would then refer the client to the DNS server for cisco.com. Finally, the DNS server for cisco.com is authoritative for that domain and would return the IP address of the host record "www", completing the resolution of www.cisco.com.

TCP

SMTP/IMAP & https/http, ssh, ftp, ICMP

When designers follow accepted standards and protocols, which of the four basic characteristics of network architecture is achieved?

Scalability

Which statement correctly describes data transmission at the transport layer?

Segmentation is handled at Layer 4 by TCP sequence numbers. UDP does not have sequence numbers in the header, but instead, lets the application handle reordering if it is necessary. Only TCP provides reliable deliver and retransmits data. Each segment has either a TCP header or a UDP header; it cannot contain both.

Which of the following would be valid source and destination ports for a host connecting to an email server?

Source: 49152, Destination: 25

Which of the following would be valid source and destination ports for a host connecting to a DNS server?

Source: 49152, Destination: 53

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?

The TCP/IP implementation is functional. The ping 127.0.0.1 command is used to verify that the TCP/IP stack is functional.

What field is used to provide flow control?

The Window Size field is used to provide flow control.

A client is establishing a TCP session with a server. How is the acknowledgment number in the response segment to the client determined?

The acknowledgment number field is modified by adding 1 to the randomly chosen initial sequence number in response to the client.

> config t error

The administrator must first enter privileged EXEC mode before issuing the command.

What does a client application select for a TCP or UDP source port number?

The client randomly selects an available source port in the range of the registered ports.

Refer to the exhibit. Host A and the file server have established a TCP session to exchange data. What acknowledgement number will the file server send to host A to acknowledge receipt of the first three segments of data?

The file server will send back an acknowledgement number of 3001 to host A after receiving the first three segments. The starting sequence number was 1. 1000 bytes were sent in each of the three segments for a total of 3000 bytes. Because the initial sequence number was 1, the last byte sent was byte number 3000. The file server will now expect to receive byte number 3001 and above.

Assume a host with IP address 10.1.1.10 wants to request web services from a server at 10.1.1.254. Which of the following would display the correct socket pair?

The socket pair for a host with IP address 10.1.1.10 requesting web services from a server at 10.1.1.254 would be 10.1.1.10:1099, 10.1.1.254:80.

The global configuration command ip default-gateway 172.16.100.1 is applied to a switch. What is the effect of this command?

The switch can communicate with other hosts on the 172.16.100.0 network. A default gateway address is typically configured on all devices to allow them to communicate beyond just their local network.In a switch this is achieved using the command ip default-gateway <ip address>.

Which field in the TCP header indicates the status of the three-way handshake process?

The value in the control bits field of the TCP header indicates the progress and status of the connection.

How many exchanges are needed to end both sessions between two hosts?

There are four exchanges to end both sessions between two hosts. (1) Host A sends a FIN. (2) Host B sends an ACK. (3) Host B sends a FIN. (4) Host A sends an ACK.

A network administrator enters the service password-encryption command into the configuration mode of a router. What does this command accomplish?

This command prevents someone from viewing the running configuration passwords. The startup-config and running-config files display most passwords in plaintext. Use the service password-encryption global config command to encrypt all plaintext passwords in these files.

Which transport layer protocol statement is true?

UDP is a best-effort delivery protocol.

The six control bits flags are as follows:

URG - Urgent pointer field significant ACK - Acknowledgment flag used in connection establishment and session termination PSH - Push function RST - Reset the connection when an error or timeout occurs SYN - Synchronize sequence numbers used in connection establishment FIN - No more data from sender and used in session termination

Sequence numbers

Used to identify missing segments of data

udp

VOIP AND DNS., tftp, snmp, dhcp, video

Which DHCPv4 message will a client send to accept an IPv4 address that is offered by a DHCP server?

When a DHCP client receives DHCPOFFER messages, it will send a broadcast DHCPREQUEST message for two purposes. First, it indicates to the offering DHCP server that it would like to accept the offer and bind the IP address. Second, it notifies any other responding DHCP servers that their offers are declined.

Refer to the exhibit. When PC1 wants to send a packet to PC3, the IP address of the device that will respond to the ARP request is

When a network device has to communicate with a device on another network, it broadcasts an ARP request asking for the default gateway MAC address. The default gateway (RT1) unicasts an ARP reply with the Fa0/0 MAC address. 192.168.0.1 is Fa0/0 IPv4 on RT1

What happens when a sending host senses there is congestion?

When a sending host senses congestion, it reduces the number of bytes it sends before receiving an acknowledgment from the destination host.

What is the last segment sent to complete the termination process of a TCP session that was initiated by a client?

a segment with the ACK flag set to 1 from the server

Design layer provides connectivity to devices on an Ethernet LAN?

access

Which two TCP header fields are used to confirm receipt of data? (Choose two.)

acknowledgment number, sequence number

arp attacks

arp requests sent as broadcast and can be spoofed. known as arp poisoning.

CSMA/CD

carrier sense multiple access/collision detection one device is transmitting at a time. allows multiple devices to share the same half-duplex medium, detecting collisions . also, provides a back-off algorithm for retransmission full-duplex communications with Ethernet switches do not require access control through carrier sense multiple access/collision detection

Refer to the exhibit. PC1 issues an ARP request because it needs to send a packet to PC3. In this scenario, what will happen next?

default gateway closest to pc is fa0/0 RT1 will send an ARP reply with its own Fa0/0 MAC address. When a network device has to communicate with a device on another network, it broadcasts an ARP request asking for the default gateway MAC address. The default gateway (RT1) unicasts an ARP reply with the Fa0/0 MAC address.

scalable network

expands quickly to support new users and applications. does this without degrading the performance of services that are being accessed by existing users.

True or false? A DNS server that receives a request for a name resolution that is not within its DNS zone will send a failure message to the requesting client.

false, When a DNS server receives a name resolution request for a name not within its zone, the serve will forward the request to another DNS server.

flag

flag is a bit that is set to either on or off

tcp

flow control, reliable, sequence number

A host device needs to send a large video file across the network while providing data communication to other users. Which feature will allow different communication streams to occur at the same time, without having a single data stream using all available bandwidth?

multiplexing

Network administrators must address two types of network security concerns

network infrastructure security and information security

troubleshoot name resolution issues and to verify the current status of the name servers. allows the user to manually query the name servers to resolve a given host name

nslookup

Which two commands could be used to check if DNS name resolution is working properly on a Windows PC? (Choose two.)

nslookup cisco.com PING cisco.com

LLC Sublayer

responsible for providing a reliable communication link between two devices over a network by establishing and maintaining logical connections between them. It also handles flow control, error checking, and retransmission of lost or damaged frames. The LLC sublayer also handles addressing of devices using unique identifiers known as MAC addresses. This IEEE 802.2 sublayer communicates between the networking software at the upper layers and the device hardware at the lower layers. It places information in the frame that identifies which network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IPv4 and IPv6, to use the same network interface and media.

Which switch command would a network administrator use to determine if there are encapsulation or media errors on an interface?

show interfaces

show arp in router

show ip arp

A user sends an HTTP request to a web server on a remote network. During encapsulation for this request, what information is added to the address field of a frame to indicate the destination?

the MAC address of the default gateway A frame is encapsulated with source and destination MAC addresses. The source device will not know the MAC address of the remote host. An ARP request will be sent by the source and will be responded to by the router. The router will respond with the MAC address of its interface, the one which is connected to the same network as the source.

Refer to the exhibit. What does the value of the window size specify?

the amount of data that can be sent before an acknowledgment is required

What is a socket?

the combination of a source IP address and port number or a destination IP address and port number

Which of the following is displayed by the nslookup utility?

the configured default DNS server

Which layer is responsible for establishing a temporary communication session between the source and destination host applications?

transport layer

type of arp

type filed of 0x806. informs the receiving NIC that the data porton of the frame needs to be passed to the ARP process.

Is connectionless, Is suitable for delay-intolerant applications, Best-effort delivery protocol

udp

fully qualified domain name (FQDN)

web url

Which port group includes port numbers for FTP, HTTP, and TFTP applications?

well known ports