Lesson 5: Configuring Network Addressing and Internet Connections Flashcards
Flashcard:
You are assisting another customer with a full fiber connection terminated to an optical network terminal (ONT). The customer’s router was disconnected while some building work was being completed, and the patch cable is now missing. The customer thinks that the cable should be a fiber optic one because the service is “full fiber.” What type of cable do you need to locate?
An RJ45 unshielded twisted pair (UTP) patch cable.
The ONT converts the optical signal over the external fiber optic cable to an electrical one to connect to the local router.
Flashcard:
You are setting up an ADSL router/modem for a client; unfortunately, the contents of the box have become scattered. What type of cable do you need to locate to connect the router’s WAN interface?
Asymmetrical Digital Subscriber Line (DSL) connects to the phone line via a filter. You need an RJ11-terminated patch cord to make the connection.
Flashcard:
True or false? A SOHO router uses an embedded modem and Ethernet adapter to forward traffic between public and private network segments over a single hardware port.
False.
The modem and Ethernet interfaces use separate ports.
Flashcard:
True or false? Both 4G and 5G cellular can be used for fixed access broadband as well as in mobile devices.
True.
These can work as an alternative to wired broadband or as a backup/failover Internet connection type. Many router models now come with a cellular radio. A subscribed identity module (SIM) card from the service provider must also be installed.
Flashcard:
A host is configured with the IP address 172.16.1.100 in the 172.16.1.0/16 IP network. What value should be entered as the subnet mask?
Class B
Flashcard:
You are setting up a printer to use static IPv4 addressing. What type of format (decimal or hex) is expected in the default gateway field?
The IPv4 address of the local router interface, entered in dotted decimal format.
Flashcard:
Another technician has scribbled some notes about IPv4 addresses used in various networks associated with support tickets. One of them is assigned to the WAN interface of a SOHO router that requires troubleshooting. Which of these addresses must it be?
52.165.16.254
192.168.100.52
169.254.1.121
172.30.100.32
224.100.100.1
The WAN interface of the router must use an IPv4 address from a valid public range, so 52.165.16.254 is the only one it could be
172.30.100.32 and 192.168.100.52 are in the class B and class C private ranges, 169.254.1.121 is in the range reserved for APIPA, and 224.100.100.1 is outside the range of valid public addresses (it is part of class D, which is used for a type of addressing called “multicasting”).
Flashcard:
True or false? A valid IPv6 configuration requires prefix length notation.
True
In IPv6, while there is no separate entity called a subnet mask, as in IPv4, the concept of dividing the address into network and host portions still exists and is necessary. This division is indicated by the prefix length in IPv6, such as /64, /48, etc. The prefix length in IPv6 serves the same purpose as the subnet mask in IPv4, specifying how many bits of the address are allocated for the network portion
Flashcard:
True or false? A SOHO router can be configured to provide an IPv4 address configuration to hosts without further administrator attention.
True
This service is implemented by the Dynamic Host Configuration Protocol (DHCP).
Flashcard:
True or false? At the Transport layer, connections between hosts to exchange application data are established over one port number.
False. The server application is identified by one port, but the client must also assign its own port to track the connection.
Flashcard:
Another technician has scribbled some notes about a firewall configuration. The technician has listed only the port numbers 25 and 3389. What is the purpose of the protocols that use these ports by default?
Port TCP/25 is used by the Simple Mail Transfer Protocol (SMTP) to send and receive email messages.
Port TCP/3389 is used by Remote Desktop Protocol (RDP) to connect to a computer’s graphical shell over the network.
Flashcard:
The technician has made a note to check that port 445 is blocked by the firewall. What is the purpose of the protocol that uses this port by default, and why should it be blocked?
Port TCP/445 is used by the Server Message Block (SMB) protocol that implements Windows File/Printer Sharing. SMB is designed for use on local networks only. Allowing access from the Internet would be a security risk.
Flashcard:
What feature of DHCP means that it must use UDP at the transport layer?
The Dynamic Host Configuration Protocol (DHCP) uses broadcast addressing, which is not supported by the connection-oriented Transmission Control Protocol (TCP). Consequently, DHCP uses the connectionless User Datagram Protocol (UDP).
Flashcard:
What type of address (IPv4 or IPv6) would you expect a query for an AAAA resource record to return?
An IPv6 address
Flashcard:
What type of TXT record uses cryptography to help recipient servers reject spoofed messages and spam?
DomainKeys Identified Mail (DKIM)
Flashcard:
True or false? A top-level domain such as .com represents the top of the DNS hierarchy.
False. The Domain Name System (DNS) uses root servers at the top of the hierarchy. The root is represented by a trailing dot at the end of a fully qualified domain name (FQDN), though this can very commonly be omitted in ordinary usage
Flashcard:
You need to ensure that a print device receives the same IP address when connecting to the network. What value do you need to configure on the DHCP server to enable a reservation?
The reservation should be configured with the media access control (MAC) address of the print device (plus the IP address to assign).
Flashcard:
You are advising another technician about typical DNS configuration. The technician thinks that the name server hosting the 515 support domain resource records on the Internet should be configured as the primary DNS server entry in the IP configuration of local clients. Why is this unlikely to be the case?
The role of a name server is to respond to queries for the resource records of the specific domain(s) that it is responsible for. The role of the DNS server types listed in a client’s IP configuration is to resolve requests for records in any valid domain. To do this, the resolver must take on the task of querying multiple name servers on behalf of the client. Mixing these roles on the same server machine is possible in theory, but for performance and security reasons, they are more commonly performed by separate servers.
Flashcard:
Which network configuration technology can be configured on switches to divide a local network into multiple broadcast domain segments?
Virtual LAN (VLAN)
An application uses Transmission Control Protocol (TCP) as it requires data to make it to the destination 100% intact. Which of the following are functions of this protocol? (Select all that apply.)
A. Uses SYN/ACK packets.
B. Uses TFTP.
C. Uses negative acknowledgment.
D. Uses FIN.
A. Uses SYN/ACK packets.
C. Uses negative acknowledgment.
D. Uses FIN.
*TCP establishes a connection between the sender and recipient using a handshake sequence of SYN, SYN/ACK, and ACK packets.
TCP ensures reliable delivery by using positive acknowledgments (ACKs). If an acknowledgment for a packet is not received, the sender retransmits the packet after a timeout or upon receiving duplicate ACKs.
TCP allows the graceful termination of a session using a FIN handshake. The main drawback is that this connection information requires multiple header fields.
Network devices typically use Trivial File Transfer Protocol (TFTP) to obtain a configuration file. The application protocol uses its own acknowledgment messaging, so it does not require TCP.*
A technician is sent to the personal office space of the organizations board to set up a SOHO environment for the executive. While preparing for the home installation, the technician creates a list of items that will be needed to successfully setup and configure the SOHO network. What is the function of using a switch in a SOHO environment?
A. It connects to the service provider cabling and transfers frames over the link
B. It allows local computers and other host types to connect to the network via RJ-45 ports
C. It forwards packets over the WAN interface if a location destination IP address is not available
D. It allows hosts to connect to the network over Wi-Fi
**B. It allows local computers and other host types to connect to the network via RJ-45 ports **
*When setting up and configuring a SOHO Network, a switch allows local computers and other host types to connect to the network via RJ-45 ports. This will be an unmanaged switch, so no configuration is necessary.
A modem, versus a switch, connects to the service provider cabling and transfers frames over the link. The modem type must be matched to the network type (ADSL, VDSL, or cable).
Routers, and not switches, forward packets over the WAN (Internet) interface if they do not have a local destination IP address.
An access point allows hosts to connect to the network over Wi-Fi.*
