NETWORK 007 (7) (DEC)

Which of the following IEEE wireless LAN standards define devices with a maximum aggregate channel width of 20 MHz? (Choose all correct answers.) 802.11a 802.11g 802.11n 802.11ac

A and B. Devices conforming to the IEEE 802.11a and 802.11g standards can only use a single 20 MHz channel. IEEE 802.n devices can use channel bonding to join two channels together and achieve an aggregate channel width of 40 MHz. IEEE 802.11ac devices can bond up to eight channels, for an aggregate width of 160 MHz.

Which of the following message types are exchanged by Dynamic Host Configuration Protocol (DHCP) clients and servers during a successful IP address allocation transaction? (Choose all correct answers.) DHCPDISCOVER DHCPOFFER DHCPINFORM DHCPACK DHCPREQUEST DHCPNAK DHCPRENEW DHCPRELEASE

A, B, D, and E. In a successful DHCP address allocation, the client issues DHCPDISCOVER broadcasts to locate servers, and the servers reply with DHCPOFFER messages containing addresses. Then, the client sends a DHCPREQUEST message to one server accepting an offered address, to which the server replied with a DHCPACK. DHCPNAK messages are only used in unsuccessful transactions, and DHCPRENEW, DHCPRELEASE, and DHCPINFORM messages are not used during the address allocation process.

Which of the following features is supported by DHCP, but not by BOOTP and RARP? Dynamic address allocation Relay agents Manual address allocation Automatic address allocation

A. Dynamic Host Configuration Protocol (DHCP) can dynamically allocate IP address to clients and reclaim them when their leases expire. Bootstrap Protocol (BOOTP) and Reverse Address Resolution Protocol (RARP) can allocate addresses automatically or manually, but they cannot reclaim them. DHCP and BOOTP both support relay agents.

Ed is the overnight manager of his company's datacenter, and he is responsible for both private and public resources in the company's hybrid cloud. Due to a new TV commercial shown that night, the company's website experiences a massive upsurge in traffic. The web server farm on the private cloud is being overwhelmed, so Ed configures some virtual machines in the public cloud to take up the slack. Which of the following is a common term for what Ed has done? Cloud busting Cloud bursting Cloud splitting Cloud migrating

B. Cloud bursting is a common term for the offloading of excess traffic from private to public cloud resources when necessary to maintain satisfactory performance levels.

Which of the following Dynamic Host Configuration Protocol (DHCP) options prevents the client from transmitting IP datagrams that circulate endlessly around the network? Interface MTU Default IP TTL ARP cache timeout TCP keepalive interval

B. The Default IP Time-to-live (TTL) option specifies the maximum number of seconds or hops allowed to an IP datagram before a router removes it from the network. This prevents datagrams from circulating endlessly. The Interface Maximum Transmission Unit (MTU) option specifies the maximum size of an IP datagram. The Address Resolution Protocol (ARP) cache timeout specifies how long entries containing the IP address assigned by the server can remain in the cache maintained by a client's ARP implementation. The Transmission Control Protocol (TCP) keepalive interval option specifies the number of seconds that the client should wait before transmitting a keepalive message over a TCP connection.

Which IP address allocation method is not supported by Dynamic Host Configuration Protocol (DHCP)? Manual Dynamic Stable Automatic

C. Stable is not a DHCP allocation method. DHCP supports three allocation methods: manual, dynamic, and automatic.

Which of the following TCP/IP parameters, configured on an end system, specifies the IP address of a device that performs domain name resolution services? WINS Server Addresses Default Gateway DNS Server Addresses Subnet Gateway

C. The DNS Server Addresses parameter contains the addresses of servers that resolve domain names into IP addresses. Windows Internet Name Service (WINS) provides Network Basic Input/Output System (NetBIOS) name resolution. The Default Gateway parameter defines the local router to be used to access other networks. There is no such parameter as Subnet Gateway.

Alice has just created a new Windows Server 2016 virtual machine using remote controls provided by a cloud service provider on the Internet. Which of the following cloud architectures is she using? (Choose all correct answers.) IaaS PaaS SaaS Public cloud Private cloud Hybrid cloud

A and D. Infrastructure as a Service (IaaS) provides the consumers like Alice with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. In the public cloud model, one organization functions as the provider, and another organization—in this case, Alice—consumes the services of the provider. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server furnished by the provider. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers, but the consumers have no control over the operating system, the servers, or the underlying resources. In a private cloud, the same organization that utilizes the cloud services is also the sole owner of the infrastructure that provides those services. A hybrid cloud is a combination of public and private infrastructure so that the consumer organization is only a partial owner of the infrastructure.

In which of the following DNS transactions does the querying system generate a recursive query? (Choose all correct answers.) A DNS client sends the server name www.adatum.com from a URL to its designated DNS server for resolution. A client's DNS server sends a request to a root domain server to find the authoritative server for the com top-level domain. A client's DNS server sends a request to the com top-level domain server to find the authoritative server for the adatum.com domain. A client's DNS server, which has been configured to function as a forwarder, sends the server name www.adatum.com from a URL to its ISP's DNS server for resolution. A client's DNS server sends a request to the adatum.com domain server to find the IP address associated with the server name www.

A and D. When a client sends a name resolution query to its DNS server, it uses a recursive request so that the server will take on the responsibility for resolving the name. The only other use of recursive requests is in the case of a forwarder, which is configured to pass that responsibility on to another server. All of the other queries issued by the client's server to the various domain authorities are iterative queries.

Which of the following protocols are responsible for assigning IP addresses to hosts? (Choose all correct answers.) Dynamic Host Configuration Protocol (DHCP) Address Resolution Protocol (ARP) Domain Name System (DNS) File Transfer Protocol (FTP) Bootstrap Protocol (BOOTP)

A and E. DHCP and BOOTP are both designed to allocate IP addresses to hosts. The primary difference between the two is that DHCP is capable of dynamic allocation and BOOTP is not. DNS resolves hostnames into IP addresses, and ARP resolves IP addresses into data link layer hardware (or MAC) addresses. FTP is designed to transfer files between systems and has no role in IP address allocation.

Which of the following devices would you most likely configure to function as a Dynamic Host Configuration Protocol (DHCP) server? A wireless router An unmanaged switch A hub A bridge

A. Most wireless routers are designed to provide connecting workstations with IP addresses and other TCP/IP configuration parameters. Switches and bridges are data link layer devices and hubs are physical layer devices, none of which are capable providing clients with network layer IP addresses.

Which of the following is not a protocol used to allocate IP address assignments to clients on a network? ARP RARP BOOTP DHCP

A. Reverse Address Resolution Protocol (RARP), Bootstrap Protocol (BOOTP), and Dynamic Host Configuration Protocol (DHCP) are all protocols that are designed to allocate IP addresses to clients. Address Resolution Protocol (ARP), on the other hand, resolves existing IP addresses into data link layer MAC (or hardware) addresses.

Which of the following cloud service models enables you to select the operating system you want to install? IaaS PaaS SaaS All of the above

A. The Infrastructure as a Service (IaaS) model provides consumers with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server installed by the provider. Software as a Service (SaaS) provides consumers with access to specific applications running on the provider's servers.

Which of the following cloud service models provides the consumer with the most control over the cloud resources? IaaS PaaS SaaS IaaS, PaaS, and SaaS all provide the same degree of control.

A. The Infrastructure as a Service (IaaS) model provides the consumers with the most control, as the provider furnishes processing, storage, and networking resources that the consumer can use as needed. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server furnished by the provider, but they have only limited control over the server and no control over the underlying resources. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers, but the consumers have no control over the operating system, the servers, or the underlying resources.

Which of the following Domain Name System (DNS) resource record types specifies the IP addresses of the authoritative DNS servers for a particular zone? NS PTR MX SRV

A. The Name Server (NS) resource record identifies the authoritative servers for a particular DNS zone. Pointer (PTR) resource records are used to resolve IP addresses into hostnames. Mail Exchange (MX) records identify the mail servers for a particular domain. Service Locator (SRV) records identify the designated servers for a particular application.

Which of the following options should you configure on a Dynamic Host Configuration Protocol (DHCP) server to supply clients with a default gateway address? Router Time Server Name Server LPR Server

A. The Router option specifies the addresses of routers on the local network, including the default gateway router. The Time Server option specifies the addresses of servers providing time signals to the network. The Name Server option specifies the addresses of up to ten name resolution servers (other than DNS servers) on the network. The LPR Server option specifies the addresses of line printer servers on the network.

Which of the following best describes what happens when a DNS server receives an iterative name resolution query? The DNS server responds immediately to the query with the best information it has in its resource records or in its cache or, failing that, with an error message stating that it could not resolve the requested name. The DNS server attempts to resolve the requested name by checking its own resource records and cache or, failing that, by issuing its own iterative queries to other DNS servers. The DNS server attempts to resolve the requested name by checking its own resource records and cache or, failing that, by forwarding the name resolution request to another DNS server in a recursive query. The DNS server responds immediately if it is the authoritative server for the domain in which the requested name is located. Otherwise, it returns an error message stating that it could not resolve the requested name.

A. When a DNS server receives an iterative query, it responds immediately with the best information that it has available or with an error message. It does not send queries to other servers.

In designing a network for a client, Ed has decided to use both internal and external DNS servers. Which of the following resources should Ed register with the external DNS server? (Choose all correct answers.) Company database servers Internet web servers Incoming email servers Domain controllers

B and C. The external DNS server should contain records only for the resources that must be accessible from the Internet, such as web servers and public email servers. For security reasons, servers containing sensitive data, such as database servers and domain controllers, should be registered on the internal DNS server.

Why is it necessary to use a relay agent to enable a Dynamic Host Configuration Protocol (DHCP) server to assign IP addresses to clients on other networks? (Choose all correct answers.) Because DHCP requires a separate license for each subnet Because clients cannot initiate an address assignment by contacting DHCP servers on other networks directly Because DHCP must use the Transmission Control Protocol (TCP) to communicate with clients Because the DHCP address assignment process relies on broadcast transmissions

B and D. DHCP clients cannot contact servers on different networks to initiate an address assignment. Clients locate DHCP servers by transmitting broadcast messages, and broadcasts are limited to the local network. Relay agents forward the broadcast messages to other networks, enabling the server to assign IP addresses to clients on other subnets. DHCP does not require special licenses. DHCP uses User Datagram Protocol (UDP) transmissions, not TCP.

Ralph has configured a server called NE6 to function as a web server. He does not want to change the server's existing name, but he wants it to be accessible to clients using the name www. What Domain Name System (DNS) modification can Ralph make to accomplish this? Create an additional A resource record. Create a new CNAME resource record. Modify the existing A resource record. Create a new PTR resource record.

B. A canonical name (CNAME) resource record specifies an alternative host name (or alias) for a system already registered in the DNS. By creating a CNAME record specifying the www name, the server can be addressed using either NE6 or www. Creating an additional A resource record will cause the server to be recognized using one name or the other, but not both. Modifying the existing A record will change the hostname. PTR resource records are used only for reverse name resolution.

Dynamic Host Configuration Protocol (DHCP) clients rely on which of the following types of transmissions to locate and initiate contact with DHCP servers on the local network? Unicast Broadcast Multicast Anycast

B. DHCP clients use broadcasts to transmit DHCPDISCOVER messages on the local network. DHCP servers are then required to respond to the broadcasts. DHCP clients cannot use unicast, multicast, or anycast messages to initiate contact with DHCP servers because they have no way of learning their addresses.

Which of the following technologies enables the IP addresses assigned to clients by a Dynamic Host Configuration Protocol (DHCP) server to be automatically added to the DNS namespace? Reverse name resolution Dynamic DNS Automatic allocation HOSTS

B. Dynamic DNS (DDNS) is an addition to the DNS standards that eliminates the need for administrators to manually create certain DNS resource records. For example, when a DHCP server allocates an address to a client, DDNS creates a host (A) record containing the host name of the client and the newly allocated IP address. Reverse name resolution is the process of looking up host names based on IP addresses. Automatic allocation is a DHCP process by which IP addresses are permanently assigned to clients. HOSTS is a text-based name resolution method that predates DNS.

Which of the following DHCP address allocation methods enables the server to reclaim IP addresses when they are no longer in use by clients? Automatic Dynamic Manual Static

B. Dynamic allocation enables a Dynamic Host Configuration Protocol (DHCP) server to lease IP addresses to clients for a specific time interval. When the lease period expires, the client can renew it, if it is still using the address. If the address is no longer in use when the lease expires, it is returned to the scope for reallocation. Automatic allocation permanently assigns an IP address from the scope to a client. Manual and static allocation are two terms describing the allocation of a specific IP address to a specific client.

In which of the following cloud models does a single organization function as both the provider and the consumer of all cloud services? Public cloud Private cloud Hybrid cloud Ad hoc cloud

B. In a private cloud, the same organization that utilizes the cloud services is also the sole owner of the infrastructure that provides those services. In the public cloud model, one organization functions as the provider, and another organization consumes the services of the provider. A hybrid cloud is a combination of public and private infrastructure so that the consumer organization is only a partial owner of the infrastructure. There is no such thing as an ad hoc cloud model.

On a Dynamic Host Configuration Protocol (DHCP) server, what is the name of the element you create to specify which IP addresses the server should assign to clients? Range Scope Pool Subnet

B. On a DHCP server, you create a scope that consists of a beginning and an ending IP address. Range, pool, and subnet are not technical terms for DHCP.

Which of the following features enables an intrusion detection system (IDS) to monitor all of the traffic on a switched network? Stateful packet inspection Port mirroring Trunking Service dependent filtering

B. Port mirroring is a feature found in some switches that takes the form of a special port that runs in promiscuous mode. This means that the switch copies all incoming traffic to that port, as well as to the dedicated destination ports. By connecting an IDS or protocol analyzer to this port, an administrator can access all of the network's traffic. Stateful packet inspection is a firewall feature that enables the device to examine network and transport layer header fields, looking for patterns that indicate damaging behaviors, such as IP spoofing, SYN floods, and teardrop attacks. Trunking is a switch feature that enables administrators to create VLANs that span multiple switches. Service dependent filtering is a firewall feature that blocks traffic based on transport layer port numbers.

Ed has just created a new Windows application for his company, and he wants to deploy it in the public cloud. He is looking for a provider that will furnish his company with a fully installed and configured Windows server on which he can install and run his application. Which of the following service models is he seeking to use? IaaS PaaS SaaS None of the above

B. The Platform as a Service (PaaS) model provides consumers with the ability to install applications of their choice on a server furnished by the provider. Infrastructure as a Service (IaaS) provides the consumers with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers.

Which of the following Domain Name System (DNS) resource records is used to implement email security mechanisms such as Sender Policy Framework and DomainKey Identified Mail? MX PTR TXT CNAME

C. A TXT resource record contains a text string that can be used for various applications. Sender Policy Framework (SPF) inserts a list of authorized email hosts into the TXT record and DomainKey Identified Email (DKIM) inserts a public key. MX, PTR, and CNAME records are not used for SPF and DKIM. A Mail Exchange (MX) record specifies the mail server that the domain should use. Pointer (PTR) records also contain host names and IP addresses, but they are used for reverse name resolution, that is, resolving IP addresses into host names. Canonical name (CNAME) records specify aliases for a given host name.

Which of the following statements about cloud delivery models is true? A public cloud is inherently insecure because anyone can access it. A private cloud consists of hardware that is all located in a single datacenter. A hybrid cloud enables administrators to migrate services between public and private resources. Public, private, and hybrid clouds all utilize the same hardware resources.

C. A hybrid cloud consists of both public and private resources. One of its main advantages is that administrators can move services from private to public cloud servers and back again as needed, depending on the current workload. Public cloud resources require authentication, so while they might be less secure than a private cloud, they are not inherently insecure. The term private cloud refers to hardware resources that are owned and operated by a single organization, regardless of their location. The various cloud delivery models do not impose specific hardware resource requirements.

Which of the following Domain Name System (DNS) resource records is used to resolve a hostname into an IPv6 address? MX PTR AAAA CNAME

C. An AAAA resource record maps a hostname to an IPv6 address for name resolution purposes. A Mail Exchange (MX) record specifies the mail server that the domain should use. Pointer (PTR) records also contain hostnames and IP addresses, but they are used for reverse name resolution—that is, resolving IP addresses into hostnames. Canonical name (CNAME) records specify aliases for a given hostname.

Which of the following is a tool that integrates DHCP and DNS so that each is aware of the changes made by the other? HOSTS DHCPv6 IPAM APIPA

C. IP address management (IPAM) is a system for planning, managing, and monitoring the IP address space for an entire enterprise network. IPAM provides links between the Dynamic Host Configuration Protocol (DHCP) and the Domain Name System (DNS) so that each is aware of the naming and addressing changes made by the other. DHCPv6 is an IPv6 version of the DHCP service, which enables it to allocate IPv6 addresses to network clients. HOSTS is a text-based name resolution method that predates DNS. Automatic Private IP Addressing (APIPA) is the mechanism that enables a DHCP client to assign itself an address when no DHCP servers are accessible.

Which of the following must you create on a DHCP server if you want it to always assign the same IP address to a particular computer? Exclusion Scope Reservation Relay

C. On a DHCP server, a reservation is a permanent IP address assignment to a specific MAC address. A scope is a range of IP addresses to be allocated to clients. An exclusion is a range of IP addresses that is to be excluded from a scope. A relay is a component that routes DHCP traffic between networks.

Microsoft's Outlook.com email service is an example of which of the following cloud service models? IaaS PaaS SaaS None of the above

C. Software as a Service (SaaS) provides consumers with access to a specific application running on the provider's servers, in this case an email service. Consumers have control over some of their email functions, but they have no control over the operating system, the servers, or the underlying resources. The Infrastructure as a Service (IaaS) model provides the consumers with access to processing, storage, and networking resources that the consumer can use as needed. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server furnished by the provider.

What is the maximum number of transmit and receive antennae supported by the currently ratified IEEE 802.11 wireless LAN standards? 2 4 8 16

C. The 802.11ac standard supports multiple input and multiple output (MIMO) through the use of up to eight antennae on a single device. The 802.1n standard is the only standard that supports MIMO, with up to four antennae.

Which of the following is the term for the network name that you use to connect a client device to an access point on a wireless LAN? BSS ESS SSID BSSID

C. The Service Set Identifier (SSID) is the name that you use when connecting to a wireless network. A Basic Service Set (BSS) refers to the wireless network itself, consisting of a single access point and a number of clients. An Extended Service Set (ESS) consists of two or more BSSs, using multiple access points. The Basic Service Set Identifier (BSSID) is the MAC address of the access point associated with a BSS.

When you contract with a provider to obtain email services for your company using their servers in the public cloud, which of the following service models are you using? IaaS PaaS SaaS None of the above

C. The Software as a Service (SaaS) model provides consumers with access to a specific application running on the provider's servers. Infrastructure as a Service (IaaS) provides the consumers with processing, storage, and networking resources that they can use to install and run operating systems and other software of their choice. Platform as a Service (PaaS) provides consumers with the ability to install applications of their choice on a server installed by the provider.

Which of the following message types are exchanged by Dynamic Host Configuration Protocol (DHCP) clients and servers during a successful IP address lease renewal transaction? (Choose all correct answers.) DHCPDISCOVER DHCPOFFER DHCPINFORM DHCPACK DHCPREQUEST DHCPNAK DHCPRENEW DHCPRELEASE

D and E. In a successful DHCP address renewal transaction, the client issues a DHCPDREQUEST message, and the server replies with a DHCPACK. DHCPNAK messages are only used in unsuccessful transactions, and the other message types are not used during the address renewal process.

Which of the following Domain Name System (DNS) resource records is used only for reverse name resolution? MX AAAA CNAME PTR

D. Like A and AAAA records, Pointer (PTR) records contain hostnames and IP addresses, but they are used for reverse name resolution—that is, resolving IP addresses into hostnames. A Mail Exchange (MX) record specifies the mail server that the domain should use. Canonical name (CNAME) records specify aliases for a given host name. An AAAA resource record maps a hostname to an IPv6 address for name resolution purposes.

Which of the following IEEE 802.11 wireless LAN standards are capable of supporting both the 2.4 GHz and 5 GHz frequencies? 802.11a 802.11b 802.11g 802.11n 802.11ac

D. Only the 802.11n standard defines wireless LAN devices that can support both 2.4 GHz and 5 GHz frequencies. The 802.11a and 802.11ac standards use only 5 GHz, and the 802.11b and 802.11g standards use only 2.4 GHz.

Which of the following protocols is used to synchronize computer clocks to a time signal provided by a server? TFTP HTTP SMTP NTP

D. The Network Time Protocol (NTP) is used to synchronize computer clocks. Time signals can be provided by internal servers or time servers on the Internet. The Trivial File Transfer Protocol (TFTP) is used to transfer files between systems without authentication. The Hypertext Transfer Protocol (HTTP) is used to exchange web traffic between clients and servers. The Simple Mail Transfer Protocol (SMTP) is used to transmit email traffic between clients and servers.

What is the term used to refer to the DNS client mechanism that generates name resolution queries and sends them to DNS servers? Requestor Forwarder Authority Resolver

D. The client component of the Domain Name System is called the resolver. Requestor is a generic term for any system issuing requests, and only DNS servers can be authorities or forwarders.

Which of the words in the fully qualified domain name (FQDN) www.paris.mydomain.org represents the topmost layer in the DNS namespace hierarchy? www paris mydomain org

D. The topmost layer in the DNS hierarchy is represented by org, which is a top-level domain. mydomain is a second-level domain registered by a particular organization. Paris is a subdomain within mydomain, and www is the name of a particular host in the paris.mydomain.org domain.