Computer Networks

Lookups in Informatica are classified into two types: Connected lookup (part of the data flow pipeline, receives input rows directly) and Unconnected lookup (called from within another transformation using :LKP reference, not directly in data flow). Active and passive refer to transformation types, not lookup categories. Connected vs unconnected determines how the lookup is invoked and whether it's part of the main flow.

The cluster manager in Serviceguard handles node membership - tracking which nodes join, leave, or fail in the cluster. It coordinates membership changes during reconfiguration. Heartbeat monitoring is typically handled by separate cluster communication protocols, not the membership manager itself.

RS-485 uses differential signaling over a twisted pair of wires to transmit data, which provides high noise immunity. Single-ended transmission, where signals are referenced to a common ground, is used by standards like RS-232.

802.11a operates in the 5 GHz frequency band and supports a maximum theoretical data rate of 54 Mbps. It was one of the first high-speed wireless standards. Options A, C, and D are incorrect - 100 Mbps is closer to 802.11n/g speeds in ideal conditions, while 24 and 10 Mbps are far below 802.11a's specification.

IEEE 802.3z is the standard for Gigabit Ethernet (1000 Mbps). In contrast, 802.3u defines Fast Ethernet (100 Mbps), and 802.3 is the original base standard for Ethernet. The letter suffixes denote different speed and media specifications.

DLCI (Data Link Connection Identifier) is the identifier used in Frame Relay to determine which virtual circuit a frame belongs to. Each DLCI identifies a specific PVC (Permanent Virtual Circuit) through the Frame Relay network. DTE and DCE are devices, and LMI is a signaling protocol, but only DLCI identifies the channel.

WCF (Windows Communication Foundation) was designed specifically to provide a unified programming model that abstracts and encapsulates various distributed communication technologies. This includes MSMQ for queued messaging, .NET Remoting for cross-application communication, and ASMX for legacy XML web services - allowing developers to use a single framework instead of learning multiple technologies.

Unacknowledged connectionless service means the sender transmits frames without waiting for acknowledgments. Each frame is independent and there's no connection setup. This is simple but provides no reliability guarantees.

CNE (Certified Novell Engineer) is a professional certification for network administrators using Novell NetWare. It was a widely recognized certification in the 1990s for Novell networking products.

Sockets provide an interface for programming at the Transport layer of the OSI model, enabling applications to use TCP or UDP protocols for network communication. The Application layer uses socket services but doesn't define the socket interface itself.

Firewalls can be implemented as hardware devices (network appliances, dedicated firewall appliances), software (host-based firewalls on individual machines, or software firewalls running on general-purpose hardware), or a combination of both approaches. Hybrid implementations are common in enterprise environments. Option C correctly captures this implementation flexibility.

In a join component, the driving port should be the one receiving the larger amount of data. This optimizes performance because the join operation processes data more efficiently when driving from the larger dataset.

DTE stands for Data Terminal Equipment, which refers to end-user devices in a network (like computers, terminals) that initiate or terminate data communication. DTE interfaces with DCE (Data Circuit-Terminating Equipment) like modems to communicate over networks.

DCE stands for Data Circuit-terminating Equipment (also known as Data Communications Equipment in some contexts). It's the network-side device that connects DTE (Data Terminal Equipment) to the network - examples include modems, CSU/DSU units. The 'C' represents Circuit or Communications in this context.

NFS stands for Network File System, a distributed file system protocol allowing a user on a client computer to access files over a network much like local storage. It's commonly used in Unix/Linux environments for sharing files across systems.