Computer Networks

DNS primarily uses UDP for queries because it's fast and lightweight. Most DNS queries fit in a single UDP packet, making it the standard protocol. TCP is only used for zone transfers or when responses are very large.

IPSec (Internet Protocol Security) can be configured to block specific ports by creating filters that deny traffic on certain port numbers. While Windows Firewall is more commonly used for port blocking today, IPSec was historically used for this purpose. The other options are unrelated to port blocking.

ARP (Address Resolution Protocol) resolves IP addresses to MAC (Ethernet) addresses within a local network. When a device needs to send data to another device on the same network, it uses ARP to discover the target's hardware address. It does not resolve domain names or hostnames.

Static NAT creates a permanent one-to-one mapping between a private IP address and a public IP address, allowing the internal host to be consistently reachable from the internet. This is commonly used for servers that need to be accessible externally. The other options incorrectly describe NAT functionality.

MRTG (Multi Router Traffic Grapher) is a network monitoring tool that measures and visualizes traffic load on network links. It creates graphs showing bandwidth usage over time, helping administrators identify congestion patterns and plan capacity.

WPA (Wi-Fi Protected Access) and SSH (Secure Shell) are security protocols used to encrypt communications. WP likely refers to WPA. HTTPD is a web server software, not a security mechanism.

The Return port is specific to unconnected lookup and is used to return the lookup value when the lookup function is called from an expression. Connected lookups pass values through output ports directly, while unconnected lookups require a Return port to send the result back to the calling transformation via the lookup function.

The netstat command is used to display network connections and identify servers connected to a domain. It shows active TCP connections, ports the server is listening on, and can reveal connected servers or services. prstat monitors process statistics, jvmstat is for Java Virtual Machine monitoring, while xtstat and mvstat are not standard network utilities.

The netsh command enables the Remote Administration rule group in Windows Firewall, allowing management tools from remote systems. Option A is for OCs setup, B is registry scripting, C lists OCs.

Hyper-V supports Automatic Private IP Addressing (APIPA) for self-configuring addresses when DHCP fails, Dynamic IP addresses via DHCP, and Static IP addresses configured manually. Classless IP Addressing (D) refers to CIDR notation, not a distinct IP address type.

The Enterprise Media Manager (EMM) server is the NetBackup component that manages resources (tape drives, media, storage units). In standard NetBackup architecture, EMM runs on the Master Server and contains the relational database tracking all backup resources and policies.

The robtest utility in NetBackup is specifically designed for testing and managing robotic tape libraries. It allows administrators to view and manipulate the contents of media access ports (MAPs), which are the entry/exit points for tapes in the robotic library. Other utilities like vmquery, tpconfig, and tpautoconf serve different purposes for volume management and device configuration.

Server groups in NetBackup can include Master servers, Media servers, and NDMP tape servers. EMM (Enterprise Media Manager) servers and NOM (NetBackup Operations Manager) servers cannot be added to server groups as they serve different management functions.

To route traffic through the backup network, the media server must use its -bkup hostname (B) so clients can connect via that interface. Clients also need the -bkup hostname in their NetBackup server list (C) to know which address to use. Configuring client-side network settings (A) or adding clients to media server lists (D) won't direct the traffic correctly.

Variable ports are NOT available in Router transformation. Expression, Aggregator, and Rank transformations all support variable ports for intermediate calculations, but Router only has input, output, and group ports for routing data based on conditions.