certmaster Explaining Network Applications Flashcards
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
A
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).
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
B, C
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.
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
C
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 21. The server then opens a random high port and sends it to the client over the control connection using the PORT command, then the client initiates the data connection.
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
A, D
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.
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
A
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.
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
D
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.
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)
A
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.
An organization is converting from landline telephones to VoIP handsets. Some of the current landline locations do not have electrical outlets nearby. What can the organization use to power the replacement handsets in these cases? (Select all that apply.)
A.PoE
B.Batteries
C.LAN port
D.PBX
A, B
Handsets can use Power over Ethernet (PoE), if available, to avoid the need for separate power cabling or batteries.
Handsets can use batteries or Power over Ethernet (PoE), if available and there is no other power source available nearby.
In a typical voice VLAN configuration, the LAN port on the handset plugs into the wall port, while the PC plugs into the PC port on the handset and separate VLAN IDs distinguish voice traffic from data traffic.
A private branch exchange (PBX) is an automated switchboard providing a single connection point for an organization’s voice lines.
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
B
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.
