Networking Devices and Initial Configuration Module 7 - 9

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

They are received and processed by every device on the local network. 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.

Which network server is malfunctioning if a user can ping the IP address of a web server but cannot ping the web server host name?

the DNS server If pings are successful to an IP address but not to a host name, then the problem may be that a DNS server cannot be accessed.

Which protocol is used by a computer to find the MAC address of the default gateway on an Ethernet network?

ARP

Which protocol is used to discover the destination address needed to be added to an Ethernet frame?

ARP In the data link layer, a frame header is added. The frame header includes the source and destination MAC addresses. In order to find the MAC address of the destination host, the sending host uses the Address Resolution Protocol (ARP). If the destination host is not on the same LAN, the MAC address of the default gateway is used as the destination MAC address in the frame header.

Match each description with the corresponding TCP mechanism.

Acknowledgment- Received by a sender before transmitting more segments in a session Retransmission- Method of managing segments of data loss Sequence numbers- Used to identify missing segments of data Acknowledgmentwindow size- Number of bytes a destination device can accept and process at one time

Which statement correctly describes data transmission at the transport layer?

Both UDP and TCP use port numbers.

A host PC has just booted and is attempting to lease an address through DHCP. Which two messages will the client typically broadcast on the network? (Choose two.)

DHCPREQUEST DHCPDISCOVER

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 Both the client and server will send a FIN and an ACK flagged segment to end each of the one-way TCP sessions in a single conversation.

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.

What will a host do first when preparing a Layer 2 PDU for transmission to a host on the same Ethernet network?

It will search the ARP table for the MAC address of the destination host.

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

Length Source Port Checksum

Which statement is true about DHCP operation?

The client broadcasts a DHCPDISCOVER message to identify any available DHCP servers on the network. A DHCP server replies with a DHCPOFFER message. This message offers to the client a lease that contains such information as the IP address and subnet mask to be assigned, the IP address of the DNS server, and the IP address of the default gateway. After the client receives the lease, the received information must be renewed through another DHCPREQUEST message prior to the lease expiration.

What is a characteristic of a TCP server process?

There can be many ports open simultaneously on a server, one for each active server application.

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 client

A cybersecurity analyst believes that an attacker is announcing a forged MAC address to network hosts in an attempt to spoof the default gateway. Which command could the analyst use on the network hosts to see what MAC address the hosts are using to reach the default gateway?

arp -a The command arp -a will display the MAC address table on a PC.

What is a characteristic of the UDP protocol?

low overhead TCP is a connection oriented protocol that provides for error recovery and guaranteed delivery mechanisms while UDP offers connectionless delivery and has fewer fields in the packet header than TCP.

Which network service automatically assigns IP addresses to devices on the network?

DHCP

Which protocol translates a website name such as www.cisco.com into a network address?

DNS Domain Name Service translates names into numerical addresses, and associates the two. DHCP provides IP addresses dynamically to pools of devices. HTTP delivers web pages to users. FTP manages file transfers.

Which destination address is used in an ARP request frame?

FFFF.FFFF.FFFF

TCP

Is connection-oriented Uses acknowledgments Has a large header

UDP

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

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

TCP mechanisms retransmit data when an acknowledgment is not received from the destination system within a set period of time. UDP is used when an application must be delivered as quickly as possible and some loss of data can be tolerated. 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.

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. The address resolution protocol (ARP) maintains a cache of MAC to IPv4 address mappings on the local computer. If there is no mapping in the cache for a specific IPv4 address, then the ARP process sends an Ethernet broadcast on the local link in an attempt to resolve the destination IPv4 address to a MAC address.

A technician is adding a new PC to a LAN. After unpacking the components and making all the connections, the technician starts the PC. After the OS loads, the technician opens a browser, and verifies that the PC can reach the Internet. Why was the PC able to connect to the network with no additional configuration?

The new PC was preconfigured to use DHCP. When the PC is connected to a network that uses DHCP, it gets the IP address settings from the DHCP server that will allow it to function on the network. All devices require at least an IP address and subnet mask to function on a LAN. DNS does not automatically configure addresses on hosts. PC virtual interfaces are not universally compatible with LANs and do not necessarily provide a host with an IP address. At this place in the course, virtual interfaces are used on network switches.

What action does a DNS server take if it does not have an entry for a requested URL?

The server checks with another DNS server to see if it has an entry. When a client types a URL to visit a web server, the browser sends a request to the DNS server with the IP address configured on the computer. When the DNS server receives the request, it checks its table to determine the IP address associated with that web server. If the local DNS server does not have an entry for the requested name, it queries another upstream DNS server. When the DNS server learns the IP address, that information is sent back to the client.

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.

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

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

What is one function of the ARP protocol?

resolving an IPv4 address to a MAC address The two main functions of the ARP protocol are to resolve an IPv4 address to a MAC address and to maintain an ARP table, which lists the resolved pairs of IPv4 address and MAC address. A device automatically obtains an IP address through DHCP. The functions of DNS include resolving (or mapping) a domain name with its IP address and maintaining a table for the domain name/IP pairs.

What type of information is contained in a DNS MX record?

the domain name mapped to mail exchange servers MX, or mail exchange messages, are used to map a domain name to several mail exchange servers that all belong to the same domain.

What is the aim of an ARP spoofing attack?

to associate IP addresses to the wrong MAC address 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.