Administrative distance is a measure of the trustworthiness of a routing protocol. The smaller the administrative distance value, the more reliable the protocol. Each routing protocol has its own default administrative distance value. OSPF has a default administrative distance of 110, which means it is more reliable than RIP (120) but less reliable than EIGRP (90) or BGP (20).

When evaluating a firewall to protect a datacenter's east-west traffic, it is important to consider traffic between VMs running on different hosts. This type of traffic is referred to as east-west traffic and is often protected by internal firewalls. By implementing firewalls, an organization can protect their internal network against threats such as lateral movement, which can be caused by attackers who have breached a perimeter firewall. Reference: Network+ Certification Study Guide, Chapter 5: Network Security

VLAN (virtual LAN) tags are used to identify packets as belonging to a particular VLAN. VLANs are used to segment a network into logical sub-networks, and each VLAN is assigned a unique VLAN tag. If the VLAN tag is not configured correctly, the computer may not be able to access network resources.

The software on the workstation should be configured to send the query to 10.1.2.255, which is the local subnet broadcast address. A broadcast address is a special address that allows a device to send a message to all devices on the same subnet. It is usually derived by setting all the host bits to 1 in the network address. In this case, the network address is 10.1.2.0/27, which has 27 network bits and 5 host bits. By setting all the host bits to 1, we get 10.1.2.31 as the broadcast address in decimal notation, or 10.1.2.255 in dotted decimal notation. Reference: https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html

The distribution layer is the layer that connects the access layer to the core layer in a hierarchical network design. The distribution layer is responsible for routing, filtering, and policy enforcement between the LAN and the WAN. A router is a layer 3 device that can perform these functions and connect to different WAN technologies.
Reference:
CompTIA Network+ N10-008 Certification Study Guide, page 151
CompTIA Network+ N10-008 Cert Guide, Deluxe Edition, page 322
CompTIA Network+ N10-008 Exam Cram, page 233