CompTIA N10-008 Practice Test - Questions Answers, Page 82

In DNS, the PTR (Pointer) record is used specifically in reverse DNS lookups to map an IP address to a domain name, which is the opposite of the more common forward DNS lookups that map domain names to IP addresses. The PTR record is the principal type of record used in reverse DNS lookups, making it the correct answer. AAAA records store IPv6 addresses, CNAME records are used for aliases, and TXT records hold text information, none of which are primarily used in reverse DNS configurations.

The session layer of the OSI model, which is Layer 5, is responsible for establishing, managing, and terminating connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogs between the applications at each end. It handles sessions using service points, which are called 'sockets.' Therefore, sockets are closely associated with the session layer as they provide the endpoint for communication sessions between client-server applications. Other options such as data representation, packets, and frames are associated with other OSI layers (presentation, network, and data link, respectively).

East-west data traffic in a data center refers to the traffic that flows laterally within the data center, typically between servers within the same data center. This type of traffic usually flows between top-of-rack (ToR) switches, which connect multiple servers or devices in the same rack to each other or to other racks without necessarily routing through the core or distribution layers of the network architecture. This is opposed to north-south traffic, which typically flows in and out of the data center to the wider network or internet. Therefore, the correct answer is 'top-of-rack switches'.

SLAAC (Stateless Address Autoconfiguration) is a method used by devices in an IPv6 network to configure their own IP addresses automatically using the link-local address and the network prefix that are advertised by routers. An error stating that there is an identical IP address already in use could occur if two devices on the network have duplicate MAC addresses. Since IPv6 addresses generated by SLAAC include the MAC address in the EUI-64 format, duplicate MAC addresses would result in identical IPv6 addresses. Options such as rogue DHCP server, incorrect router advertisement, and wrong VLAN assignment do not typically result in duplicate IP address conflicts under SLAAC since the address configuration is primarily derived from the MAC address.

A hybrid cloud model combines both on-premises infrastructure (or private cloud) with public cloud services, with orchestration between the two. This allows businesses to scale computing resources and also provides the flexibility to have on-premises infrastructure that supports average workloads while utilizing the cloud for peak loads or additional resources. The scenario described involves an on-premises data center integrated with an Infrastructure-as-a-Service (IaaS) provider via a private connection, exemplifying a hybrid cloud by utilizing both private (on-premises data center and private direct connection) and public (IaaS) cloud environments.

To set up IPv6 addressing that includes the MAC address of each connected machine, the network administrator should implement EUI-64 and SLAAC (Stateless Address Autoconfiguration). EUI-64 is a method used in IPv6 to automatically generate the interface identifier part of the address from the MAC address of the network card, thereby embedding the MAC address in the IPv6 address. SLAAC is a mechanism where a device can assign itself a unique IPv6 address in conjunction with the EUI-64 process, without the need for manual configuration or the necessity of DHCP. These two methods combined enable each device on the network to automatically configure its own IPv6 address that includes its MAC address in a stateless manner.

When connecting two unmanaged switches together, the use of a straight-through Ethernet cable is typically incorrect unless the switches support auto-mdix (automatic medium-dependent interface crossover), which automatically adjusts the connection to allow for different types of cables. Older or more basic unmanaged switches often require a crossover cable when connecting similar devices (switch-to-switch or hub-to-hub) to ensure the transmit pins on one end match the receive pins on the other end. This allows data to flow correctly between the two devices. Since the uplinks are not on, it suggests that the correct pin alignment is not being achieved with the straight-through cable, and a crossover cable should be used instead.

Given that the longer cables within the infrastructure are working correctly but the newly installed patch cables are causing connectivity issues, the most likely cause is an incorrect pinout on the patch cables. If these cables were not properly crimped according to the T568A or T568B wiring standards, they could easily cause a failure in connectivity due to incorrect alignment of the transmitting and receiving pins. This is a common issue with DIY or newly crimped cables where mistakes in the wire arrangement can render the cables non-functional. The other listed issues, such as mixed cable types, plenum rating, or cable distance exceedance, would not typically result in a total loss of connectivity as described.

Jitter is the variation in the time between packets arriving, caused by network congestion, timing drift, or route changes. In the context of VoIP, jitter is especially problematic because it affects the steady stream of packet delivery needed for coherent voice communication. When packets are received out of order, the audio can become jumbled and distorted, as the packets don't arrive in the sequence needed for correct playback. Jitter is the specific network metric responsible for causing the symptoms described in the scenario, whereas bandwidth, latency, and delay could contribute to network performance issues but would not specifically cause packets to be received out of order.