Q&A Hero

Q: Whereas traditional telephone networks allocate dedicated circuits for voice communications using circuit switching, VoIP uses _______, allowing the sharing of transmission capacity.

Q: _______ works by encoding voice information into a digital format, which can be carried across IP networks in discrete packets.

Q: In ________ real-time applications, a deterministic upper bound on jitter and high reliability takes precedence over network utilization considerations.

Q: _____ real-time applications can tolerate the loss of some portion of the communicated data.

Q: ________ is the maximum variation in delay experienced by packets in a single session.

Q: The term ___________ refers to the use of multiple forms of information, including text, still images, audio, and video.

Q: A resource within a SIP network is identified by a __________ . A) UAS B) URI C) UAC D) URL

Q: The ________ is a simple device that produces one or more outgoing RTP packets for each incoming RTP packet. A) register B) translator C) mixer D) relay

Q: A _________ is an RTP relay that receives streams of RTPpackets from one or more sources, combines these streams, and forwards a new RTP packet stream to one or more destinations. A) translator B) mixer C) location service D) registrar

Q: RFC 3550 outlines ________ as a function performed by RTCP. A) QoS and congestion control B) identification C) session control D) all of the above

Q: The _______ packet confirms to receivers that a prolonged silence is due to departure rather than network failure. A) Note B) RR C) BYE D) Timestamp

Q: The values in the __________ enable senders, receivers, and network managers to monitor conditions on the network as they relate to a particular session. A) Sender Report B) RTCP C) Timestamp D) Note

Q: An intermediary entity that acts as both a server and a client for the purpose of making requests on behalf of other clients is the ____________ . A) proxy server B) registrar C) redirect server D) user agent

Q: An example of servers are _________ . A) proxies B) redirect servers C) registrars D) all of the above

Q: SIP incorporates the use of a _________ , which defines session content using a set of types similar to those used in MIME. A) SDP B) PBX C) UAC D) DNS

Q: _________ is the determination of the media and media parameters to be used. A) Session setup B) Session management C) User capabilities D) User availability

Q: ________ is the determination of the willingness of the called party to engage in communications. A) User location B) User availability C) User capabilities D) Session management

Q: The _________ connects different physical networks in order to provide end-to-end connectivity. A) softphone B) IP PBX C) media gateway D) SIP

Q: The heart of the call placement process for VoIP is the __________ . A) PBX B) SIP C) RTP D) none of the above

Q: With __________ , the calling user supplies the phone number of a URI, which then triggers a set of protocol interactions resulting in the placement of the call. A) VoIP B) PBX C) RTP D) SIP

Q: _________ is a desirable property for real-time communication. A) Low overhead in header bits per packet B) Modest buffer requirements within the network C) Low jitter D) All of the above

Q: An application-level firewall may prevent the forwarding of RTP packets.

Q: The Payload Type field identifies the media type of the payload and the format of the data, including the use of compression or encryption.

Q: The RTP Timestamp is the absolute wall clock time when this report was sent.

Q: The jitter measure may provide a warning of increasing congestion before it leads to packet loss.

Q: Proxies are not useful for enforcing policy.

Q: A user agent server issues SIP requests.

Q: SIP is based on an HTTP-like request/response transaction model.

Q: SIP can support any type of single media or multimedia session, including teleconferencing.

Q: VoIP readily integrates with other services, such as combining Web access with telephone features through a single PC or terminal.

Q: A VoIP system is usually cheaper to operate than an equivalent telephone system with a PBX and conventional telephone network service.

Q: VoIP is the transmission of speech across IP-based network.

Q: Hard real-time applications impose fewer requirements on the network, and it is therefore permissible to focus on maximizing network utilization.

Q: Soft-time applications have zero loss tolerance.

Q: Real-time applications are more concerned with timing issues.

Q: The requirements of real-time traffic differ from those of high-speed but non-real-time traffic.

Q: The ________ works on behalf of user actors and user applications and is their representative within the e-mail service.

Q: The Internet mail architecture is currently defined in RFC _______ .

Q: __________ is a facility that allows users at workstations and terminals to compose and exchange messages.

Q: A ________ is a server that appears to the client as if it were an origin server. A) tunnel B) proxy C) gateway D) all of the above

Q: A _________ is a facility that may store previous requests and responses for handling new requests. A) cache B) gateway C) proxy D) tunnel

Q: HTTP is ___________ . A) a transaction-oriented client/server protocol B) a stateless protocol C) flexible in the formats it can handle D) all of the above

Q: _______ is a section in a DNS message. A) Header B) Question C) Authority D) All of the above

Q: The _______ domain is dedicated exclusively for private businesses. A) org B) net C) com D) biz

Q: _______ are server programs that hold information about a portion of the domain name tree structure and the associated RRs. A) MIME B) Name servers C) DNS databases D) Domain name space

Q: ________ are programs that extract information from name servers in response to client requests. A) Resolvers B) DNS databases C) Domain name spaces D) MIME

Q: ________ is an Internet standard defined in RFC 1939 that supports the basic functions of download and delete for e-mail retrieval. A) POP3 B) IMAP4 C) ADMD D) All of the above

Q: ________ supplements SMTP and allows the encapsulation of multimedia (nontext) messages inside of a standard SMTP message. A) ADMD B) MIME C) DNS D) IMAP

Q: The protocol that is used for transfer of mail from a user agent to a MTA and from one MTA to another is the _________ . A) SMTP B) MIME C) IMAP D) POP3

Q: The _______ is a directory lookup service that provides a mapping between the name of a host on the Internet and its numerical address. A) MHS B) MUA C) ADMD D) DNS

Q: A(n) ________ domain is an Internet e-mail provider. A) message store B) administrative management C) user agent D) submission agent

Q: The ________ relays mail for one application-level hop. A) MTA B) MS C) POP D) MSA

Q: The _________ is responsible for transferring the message from the MHS to the MS. A) MDA B) ADMD C) MTA D) MUA

Q: Typically, the ________ function is housed in the user's computer and is referred to as a client e-mail program or a local network e-mail server. A) MDA B) MHS C) MUA D) MTA

Q: The header section is not always present in a DNS message.

Q: When there are multiple root servers with the same name, each has an identical copy of the database for that server and the same IP address.

Q: DNS allows essentially unlimited levels and uses the comma as the level delimiter in printed names.

Q: Domains are organized hierarchically.

Q: The IP address provides a way of uniquely identifying devices attached to the Internet.

Q: IMAP always keeps messages on the server and replicates copies to the clients.

Q: RFC 824 is the format for use in constructing messages for transmission via SMTP.

Q: SMTP is limited to the conversation that takes place between the SMTP sender and the SMTP receiver.

Q: SMTP standardizes the message character set as 7-bit ASCII.

Q: POP3 is more complex than IMAP.

Q: An MUA can employ a long-term message store.

Q: The author MUA processes receive mail for storage and/or display to the recipient user.

Q: Interoperability is required among the MTA components along the transfer path through the MHS.

Q: Messages must be formatted by the MUA on behalf of the message author so that the message can be displayed to the message recipient by the destination MUA.

Q: Some e-mail systems only serve users on a single computer; others provide service across a network of computers.

Q: A _______ is a forwarding agent, receiving a request for a URL object, modifying the request, and forwarding the request toward the server identified in the URL.

Q: The ________ is the foundation protocol of the World Wide Web and can be used in any client/server application involving hypertext.

Q: Each name server is configured with a subset of the domain name space, known as a ________ , which is a collection of one or more subdomains within a domain, along with the associated RRs.

Q: DNS is based on a hierarchical database containing _________ that include the name, IP address, and other information about hosts.

Q: Four elements comprise the DNS: domain name space, DNS database, name servers, and _________ .

Q: _______ is an extension to the RFC 822 framework that is intended to address some of the problems and limitations of the use of SMTP and RFC 822 for electronic mail.

Q: The ________ accepts each arriving message and either places it in the appropriate user mailbox or copies it to the local outgoing mail queue if forwarding is required.

Q: The ________ takes messages from the outgoing mail queue and transmits them to the proper destination host via SMTP transactions over one or more TCP connections to port 25 on the target hosts.

Q: Defined in RFC 821, ______ is the standard protocol for transferring mail between hosts in the TCP/IP suite.

Q: Examples of an _________ include a department that operates a local mail relay, an IT department that operates an enterprise mail relay, and an ISP that operates a public shared e-mail service.

Q: The ________ is like a packet switch or IP router in that its job is to make routing assessments and to move the message closer to the recipients.