11) Network Applications

Question 1

A client’s browser has requested a web page. What protocol, at the Application layer of the OSI model, makes the request?

A. HTTP
B. TCP
C. HTML
D. POST

Answer 1

HTTP

The foundation of web technology is the HyperText Transfer Protocol (HTTP). HTTP enables clients (typically web browsers) to request resources from an HTTP server.

A client connects to the HTTP server using an appropriate TCP port (TCP/80, by default) and submits a request for a resource, using a uniform resource locator (URL) via the HTTP protocol.

HyperText Markup Language (HTML) web pages are plain text files with coded tags describing how the browser should format the web page.

POST is a forms mechanism feature of the HTTP protocol that enables a user to submit form data from the client to the server.

Question 2

An administrator ran a command and determined that the FQDN of a client is forbes.sales.realty.com. What is the hostname of the client?

A. com
B. sales
C. forbes
D. realty

Answer 2

c. forbes

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A fully qualified domain name (FQDN) consists of the hostname and a domain suffix. In this domain, forbes is the hostname and the domain suffix is sales.realty.com.

A fully qualified domain name (FQDN) consists of the hostname and a domain suffix. In this domain, the suffix .com is the top-level domain.

A fully qualified domain name (FQDN) consists of the hostname and a domain suffix. In this domain, sales is a domain name within the top-level domain .com.

A fully qualified domain name (FQDN) consists of the hostname and a domain suffix. In this domain, realty is a domain name within the top-level domain .com.

Question 3

An organization has multiple subnets but is only using one DHCP server. How is this possible? (Select all that apply.)

A. Stateless address autoconfiguration
B. Default gateway
C. DHCP relay
D. UDP forwarding

Answer 3

C. DHCP relay
D. UDP forwarding

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Administrators can configure a DHCP relay agent to provide forwarding of DHCP traffic between subnets to avoid provisioning and configuring DHCP servers on every subnet.

UDP forwarding is a more general application of a DHCP relay, but UDP forwarding forwards DHCP, the Network Time Protocol (NTP), and other broadcast-based applications.

In IPv6, the Stateless Address Autoconfiguration (SLAAC) process can locate routers (default gateways) and generate a host address with a suitable network prefix automatically.

A default gateway is the IP address of the router that allows devices on one subnet to communicate with devices on other subnets.

Question 4

An administrator is using DHCP and wants to retain centralized management of IP addressing but needs to ensure that specific devices that supply always-on functionality have static IP address assignments. What is the best solution?

A. Configure static assignments on those devices

B. Assign addresses from a specially configured exclusion range

C. Create reservations

D. Configure scopes

Answer 4

C. Create reservations

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To retain centralized management of IP addressing, the administrator can create a reservation which is a mapping of a MAC address or interface ID to a specific IP address within the DHCP server’s address pool.

The administrator can configure static assignments using IP addresses outside the DHCP scope; however, this does not allow the administrator to retain centralized management.

The administrator can assign IP addresses from a specially configured exclusion range; however, the administrator must statically assign them, and this does not allow the administrator to retain centralized management.

A scope is a range of IP addresses and options configured for a single subnet. Administrators define scopes by providing a start and end IP address along with a subnet mask.

Question 5

An organization is using IPv4 addresses. Which of the following records will resolve a hostname to the IP address?

A. A
B. AAAA
C. CNAME
D. Alias

Answer 5

Answer: A) A

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Administrators use an address (A) record in the domain name system to resolve a hostname to an IPv4 address using the UDP transport protocol over port 53 by default.

Administrators use an AAAA record in the domain name system to resolve a hostname to an IPv6 address. Due to the large address sizes of IPv6, AAAA records can exceed the maximum UDP packet size.

A Canonical Name (CNAME), or alias record, configures an alias for an existing address record (A or AAAA). An administrator can redirect an alias to a completely different host if needed.

An alias record, or Canonical Name (CNAME) record, configures an alias for an existing address record (A or AAAA).

Question 6

ICANN is a non-profit organization that’s dedicated to keeping the Internet secure. What does ICANN manage? (Select all that apply.)

A. Country codes
B. Generic TLDs
C. FQDNs
D. DNS

Answer 6

B. Generic TLDs
D. DNS

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ICANN (Internet Corporation for Assigned Names and Numbers) manages the generic TLDs (top level domains) such as .com, .org, .net, .info, and .biz.

ICANN manages the Domain Name System (DNS) which is a global hierarchy of distributed name server databases that contain information on domains and hosts within those domains.

Organizations appointed by the relevant government generally manage country codes such as .uk, .ca, and .de.

Organizations must register a domain name with a registrar to ensure that it is unique, but the organization that registered the domain name manages its FQDNs (fully qualified domain names).

Question 7

A user has typed www.network.com into a web browser. The domain name server cannot resolve the name, so it is querying other name servers to try to find it. What kind of lookup is the domain name server performing?

A. Iterative
B. Recursive
C. Start of authority
D. Resource record

Answer 7

B. Recursive

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A recursive lookup means that if the queried server is not authoritative, it does take on the task of querying other name servers until it finds the requested record or times out.

In an iterative lookup, a name server responds to a query with either the requested record or the address of a name server at a lower level in the hierarchy that is authoritative for the namespace.

The Start of Authority (SOA) record identifies the primary authoritative name server that maintains complete resource records for a zone.

Resource records allow a DNS name server to resolve queries for names and services hosted in the domain into IP addresses.

Question 8

An administrator is configuring the TCP/IP settings in workstations and wants to use the solution with the least amount of overhead. What setting will the administrator select?

A. UDP
B. TCP
C. IP
D. DHCP

Answer 8

D. DHCP

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The administrator will use Dynamic Host Configuration Protocol (DHCP) which provides an automatic method for allocating an IP address, subnet mask, and other optional parameters.

The User Datagram Protocol (UDP) works at the Transport layer, but unlike TCP, it is a connectionless, nonguaranteed method of communication with no acknowledgments or flow control.

The Transport Control Protocol (TCP) works at the Transport layer and is a connection-oriented, guaranteed method of communication with acknowledgments and flow control.

The Internet Protocol (IP) works at the Network layer and provides logical addressing and packet forwarding between different networks.

Question 9

An administrator is configuring a DHCP server. What configurations must the administrator apply to the server? (Select all that apply.)

A. The server must receive a dynamic IP address

B. The administrator must configure the DHCPDISCOVER packet

C. The server must receive a static IP address

D. The administrator must configure a scope

Answer 9

C. The server must receive a static IP address

D. The administrator must configure a scope

An administrator must allocate a static address to the DHCP server as network services that always need to be on should always have static IP addresses.

An administrator must configure a scope or a range (or pool) of IP addresses and subnet masks plus option values to allocate.

An administrator should not allocate a dynamic address to a DHCP server as network services that always need to be on should always have static IP addresses.

When negotiating a DHCP connection, some hosts cannot receive unicast without an IP address. They should set a broadcast bit in the DHCPDISCOVER packet.

Question 10

A client is attempting to renew its lease with the DHCP server so that it can keep the same IP addressing information. How much of the lease duration has lapsed?

A. At least 50%
B. At least 87.5%
C. At least 0
D. At least 255

Answer 10

At Least 50%

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A client can renew the lease when at least half the lease’s period has elapsed so that it keeps the same IP addressing information.

If the original DHCP server does not renew a client’s lease by the time 87.5% of the lease duration is up, the client will attempt to renew with any available DHCP Server.

DHCP options besides IP address and subnet mask have a tag byte or decimal value between 0 and 255, although the DHCP server cannot use 0 as an option value.

DHCP options besides IP address and subnet mask have a tag byte or decimal value between 0 and 255, although the DHCP server cannot use 255 as an option value.

Question 11

An organization has multiple subnets but is only using one DHCP server. How is this possible? (Select all that apply.)

A. Stateless address autoconfiguration
B. Default gateway
C. DHCP relay
D. UDP forwarding

Answer 11

C. DHCP relay
D. UDP Forwarding

=====================================

Administrators can configure a DHCP relay agent to provide forwarding of DHCP traffic between subnets to avoid provisioning and configuring DHCP servers on every subnet.

UDP forwarding is a more general application of a DHCP relay, but UDP forwarding forwards DHCP, the Network Time Protocol (NTP), and other broadcast-based applications.

In IPv6, the Stateless Address Autoconfiguration (SLAAC) process can locate routers (default gateways) and generate a host address with a suitable network prefix automatically.

A default gateway is the IP address of the router that allows devices on one subnet to communicate with devices on other subnets.

Question 12

True or False?
If a client accepts a DHCPOFFER, the DHCPREQUEST packet is broadcast on the network.

Answer 12

True

Question 13

When configuring multiple DHCP servers for redundancy, what should you take care to do?

Answer 13

Configure the servers with nonoverlapping address scopes

Nonoverlapping address scopes -

Question 14

True or False?

DHCP options can be configured on a per-scope basis.

Answer 14

True

Question 15

What is address is used to contact a DHCPv6 server?

Answer 15

IPv6 does not support broadcasts, so clients use the multicast address ff:02::1:2 to discover a DHCP server.

Question 16

In a stateless environment, what sort of information does DHCPv6 provides?

Answer 16

In a stateless environment, the host autoconfigures an address using a network prefix provided by the router (typically).
DHCPv6 is then used to provide the IPv6 addresses used to access network services , such as DNS (domain name system) or addresses used to access network services, such as DNS or SIP ( ) gateways.

Question 17

True or False?

While the client doesn’t have an IP address yet, the DHCPOFFER is usually delivered
as unicast because the server knows the client’s MAC address.

Answer 17

True

Question 18

True or False? Some hosts cannot
receive unicast without an IP address. They should set a broadcast bit in the
DHCPDISCOVER packet.

Answer 18

True

Question 19

The DHCP lease process is called the DORA process:

A. Discover, Offer, Request, and Acknowledge
B. Dynamic, Offer, Request, and Acknowledge
C. Distinct, Offer, Request, and Acknowledge
D. Develop, Offer, Request, and Acknowledge

Answer 19

A. Discover, Offer, Request, and Acknowledge

Question 20

True or False? DHCP Server Configuration

DHCP is normally deployed as a service of a network operating system or through
an appliance such as a switch or router.

A DHCP server must be allocated a dynamic
IP address and configured with a range (or pool) of IP addresses and subnet masks
plus option values to allocate.

Answer 20

False

DHCP server must be allocated a static
IP address and configured with a range (or pool) of IP addresses and subnet masks
plus option values to allocate.

Question 21

A range of addresses and options configured for a single subnet is referred to as a
____________.

A. subnet mask
B. Address resolution
C. DHCP relay agent
D. scope

Answer 21

D. Scope

To define a scope, you must provide a start and end IP address along with
a subnet mask.

The server maintains a one-to-one mapping of scopes to subnets.

That is, no scope can cover more than one subnet and no subnet can contain more
than one scope.

Question 22

There is no mechanism for a client to choose between multiple servers. Therefore, if
multiple DHCP servers are deployed—for fault tolerance, for instance—they must be
configured with nonoverlapping or split scopes.

DHCP for multiple subnets is usually
handled by configuring _________ __________ to forward requests to a central DHCP server.

A. change agents
B. host names
C. zone transfer
D. relay agents

Answer 22

D. relay agents

DHCP for multiple subnets is usually
handled by configuring relay agents to forward requests to a central DHCP server.

Question 23

A reverse DNS query returns the host name associated with a given IP address. This
information is stored in a ____________ lookup zone as a __________record.

A. NS lookup, DNS
B. reverse, pointer
C. mail (MX), service
D. recursive, FQRN

Answer 23

B. Reverse, pointer (PTR)

Question 24

An administrator updated an A (address) record, but it took the client computers approximately five minutes to recognize the change. What update can the administrator make on the resource record to allow changes to propagate through the network more quickly?

A. Increase the TTL
B. Decrease the TTL
C. DNS cache on the servers
D. DNS cache on the clients

Answer 24

B. Decrease the TTL

The administrator can decrease the time to live (TTL) value, measured in seconds, on the resource record. This value instructs how long resolvers can keep a query in cache.

If the administrator increased the time to live (TTL) value, measured in seconds, on the resource record, it would take even longer for the change to propagate through the network.

Server caching means that an updated record can be slow to propagate around the Internet. Administrators can manage this by decreasing the TTL on the resource record before a change.

Client caching means that an updated record can be slow to propagate around the Internet. Administrators can manage this by decreasing the TTL on the resource record before a change.

Question 25

A server is running Microsoft SQL Server and is replicating the data to other Microsoft SQL servers on the network. The application service is using which principal port?

A. TCP 1433
B. TCP 1521
C. TCP 3306
D. TCP 5432

Answer 25

B. TCP 1433

Microsoft SQL Server uses TCP/1433 to allow clients to connect to the database server over the network and allow replication traffic to move between database servers. Microsoft SQL Server uses TCP/1433.

Oracle’s remote data access protocol SQL*Net uses TCP/1521 to allow clients to connect to the database server over the network and allows replication traffic to move between database servers.

The open-source MySQL platform and the MariaDB platform both use TCP/3306 to allow clients to connect to the database server over the network and allows replication traffic to move between database servers.

The open-source PostgreSQL platform uses TCP/5432 to allow clients to connect to the database server over the network and allows replication traffic to move between database servers.

Question 26

A client’s browser has requested a web page. What protocol, at the Application layer of the OSI model, makes the request?

A. HTTP
B. TCP
C. HTML
D. POST

Answer 26

A. HTTP

The foundation of web technology is the HyperText Transfer Protocol (HTTP). HTTP enables clients (typically web browsers) to request resources from an HTTP server.

A client connects to the HTTP server using an appropriate TCP port (TCP/80, by default) and submits a request for a resource, using a uniform resource locator (URL) via the HTTP protocol.

HyperText Markup Language (HTML) web pages are plain text files with coded tags describing how the browser should format the web page.

POST is a forms mechanism feature of the HTTP protocol that enables a user to submit form data from the client to the server.

Question 27

An administrator is attempting to update a zone record on a name server but is unable to edit it. Why can’t the administrator edit the record?

A. It is a single zone namespace
B. It is a single name server
C. It is a secondary name server
D. It is a primary server

Answer 27

C. It is a secondary name server

It is a secondary name server which means that the server holds a read-only copy of the zone which the primary name server maintains through a replication process known as a zone transfer.

DNS name servers maintain the DNS namespace in zones. A single zone namespace might host records for multiple domains.

DNS name servers maintain the DNS namespace in zones. An administrator might configure a single-name server to manage multiple zones.

On a primary name server, the zone records held on the server are editable. As the zone records are editable on all primaries, administrators must carefully replicate and synchronize all changes.

Question 28

An organization needs to use shared mailboxes for managing customer inquiries. What mailbox access protocol should the clients utilize to retrieve the mail over secured connections?

A. POP3S
B. IMAP
C. IMAPS
D. MAPI

Answer 28

C. IMAPS

The clients should use IMAPS which is the Internet Message Access Protocol (IMAP) secured with TLS that supports permanent connections to a server and connecting multiple clients to the same mailbox simultaneously.

POP3S is the Post Office Protocol (POP) secured with TLS which works for dial-up access; the client contacts the server to download its messages and then disconnects.

Internet Message Access Protocol (IMAP) supports permanent connections to a server and connects multiple clients to the same mailbox simultaneously but connects on an unsecure port.

In a Windows environment, the proprietary Messaging Application Programming Interface (MAPI) protocol accesses Microsoft Exchange mailboxes. MAPI uses HTTPS as a secure transport protocol.

Question 29

An organization is converting from landline telephones to VoIP handsets, but still needs to use fax machines in many of the offices. What can the organization use to allow the fax machines to operate on the new VoIP system?

A. VoIP gateway
B .POTS
C. PBX
D. TDM PBX

Answer 29

A. VoIP Gateway

The organization can use a VoIP gateway to connect fax machines to a VoIP PBX. This type of device is also known as a Foreign Exchange Subscriber (FXS) gateway.

POTS is the plain old telephone service which is the legacy voice service of a one- or two-line analog interface to the local exchange and uses the public switched telephone network (PSTN).

A private branch exchange (PBX) is an automated switchboard providing a single connection point for an organization’s voice lines.

A TDM-based PBX connects to the telecommunications carrier over a digital trunk line, which will support multiple channels (inward and outward calls).

Question 30

Which of the following remote print protocols allows secure connections to a print device and allows it to advertise service capabilities over the network, provide plug-and-play installation for Windows and iOS devices, and use bidirectional status messaging?

A. Web Services for Devices (WSD)/AirPrint
B. Printer sharing
C. Port 9100
D. Internet Printing Protocol (IPP)

Answer 30

A. Web services for Devices (WSD) / AirPrint

Web Services for Devices (WSD)/AirPrint allows for secure connections to a print device and allows it to advertise service capabilities over the network, provides plug-and-play installation for Windows and iOS devices, and uses bidirectional status messaging.

Printer sharing means that a host connects to the printer (using a local or network connection) and then shares the printer object with other hosts using SMB.

Port 9100 just establishes a TCP connection to transfer raw Page Description Language (PDL) print job data and Printer Job Language (PJL) configuration and management data.

Internet Printing Protocol (IPP) uses TCP port 631 and can be a secure protocol (IPPS). It provides better support for status messaging than port 9100.

Question 31

What tools can a Windows administrator use to troubleshoot DNS issues without installing additional software? (Select all that apply.)

A. nslookup
B. dig
C. hostname –fqdn
D. ipconfig /all

Answer 31

A. nslookup
D. ipconfig /all

In a Windows environment, administrators can troubleshoot DNS name resolution with the nslookup command.

The first step in troubleshooting DNS issues is to verify the name configured on a host. In Windows, you can use the command ipconfig /all to display the FQDN of the local host.

In a Linux environment, administrators can troubleshoot DNS name resolution with the Domain Information Groper (dig) tool. Administrators can run dig pointing at a specific DNS server; otherwise, it will use the default resolver.

The first step in troubleshooting DNS issues is to verify the name configured on a host. In Linux, you can use the command hostname –fqdn to display the FQDN of the local host.

Question 32

An organization is using video conferencing to conduct meetings between different locations. Which of the following protocols provides information that allows the network stacks to adjust the quality of service parameters?

A. SIP
B. SIP URI
C. RTP
D. RTCP

Answer 32

D. RTCP

RTP Control Protocol (RTCP) is a session on each RTP stream that monitors the quality of the connection and provides reports that the network stacks can use to tune Quality of Service (QoS) parameters.

Session Initiation Protocol (SIP) endpoints are the end-user devices (also known as user agents), such as IP-enabled handsets or client and server web conference software.

A SIP Uniform Resource Indicator (URI) is a unique SIP address assigned to each device, conference, or telephony user.

Real-time Transport Protocol (RTP) enables the delivery of a stream of media data via UDP while implementing some of the reliability features usually associated with TCP communications.

Question 33

An administrator wants to ensure that nothing intercepts or modifies the communications between clients and the DNS servers. What can the administrator implement to prevent this from happening? (Select all that apply.)

A. DNSSEC
B. DNS over TLS
C. DNS over HTTPS
D. Internal DNS zones

Answer 33

B. DNS over TLS
C. DNS over HTTPS

The administrator can implement DNS over TLS (Transport Layer Security) which protects client queries from on-path attacks between the client and the DNS resolver.

The administrator can implement DNS over HTTPS (Hypertext Transfer Protocol Secure) which protects client queries from on-path attacks between the client and the DNS resolver.

Domain Name System Security Extensions (DNSSEC) authenticates name servers and proves the integrity of resource records.

Internal DNS zones refer to the domains used on the private network only. These name records should only be available to internal clients and must not be accessible from the Internet.

Question 34

A mail administrator configured the DNS server to allow connections on TCP port 53. Why would the administrator make this kind of configuration?

A.The network is using IPv6
B.The network is using IPv4
C.The network is using Windows
D.The network is using Linux

Answer 34

A. The network is using IPv6

Administrators may configure some DNS servers to allow connections over TCP port 53, as this allows larger record transfers (over 512 bytes) which may be necessary if the network is using IPv6.

DNS uses the UDP transport protocol over port 53 by default, and UDP has a maximum packet size of 512 bytes which is enough to accommodate IPv4.

Windows Active Directory requires a DNS service to be running and correctly configured, but that does not require the administrator to configure TCP port 53.

Most Linux networks also require a DNS service to be running and correctly configured, but that does not require the administrator to configure TCP port 53.

Question 35

An organization is working to secure email traffic. What are some methods the organization could use to do this? (Select all that apply.)

A. SMTP
B. STARTTLS
C. SMTPS
D. MX record

Answer 35

B. STARTTLS
C. SMTPS

The organization could use STARTTLS which is a command that upgrades an existing unsecure connection to use TLS. This is also known as explicit TLS or opportunistic TLS.

The organization could use SMTPS, the TLS version of SMTP, which establishes the secure connection before the exchange of any SMTP commands. This is also known as implicit TLS.

The Simple Mail Transfer Protocol (SMTP) specifies that the SMTP server of the sender discovers the IP address of the recipient SMTP server by using the domain name part of the recipient’s email address.

The DNS registers the SMTP servers for the domain using Mail Exchange (MX) and host (A/AAAA) records.

Question 36

An administrator is uploading configuration files to a web server using an FTP client. The client sent a PORT command to the server that contained the connection port number. Then the server opened the connection using that port number on the client and port 20 on the server. What type of FTP connection is the administrator using?

A. FTP
B. TFTP
C. Active FTP
D. Passive FTP

Answer 36

C. Active FTP

The administrator is using active FTP in which the client sends a PORT command specifying its chosen port and the server opens the data connection between that port and TCP port 20 on the server.

In FTP (File Transfer Protocol) the client connects to TCP port 21 on an FTP server and opens a dynamic client port number. However, data transfer cannot happen over FTP.

Trivial File Transfer Protocol (TFTP) is a connectionless protocol running over UDP port 69.

In passive FTP the client opens a data port and sends the PASV command to the server’s control port. The server then opens a port and sends it to the client, then the client initiates the connection.