Switches operate at Layer 2 and Layer 3 of the OSI model. Here's a brief explanation for each layer:
Layer 2 (Data Link Layer):
Switches primarily operate at this layer.
They use MAC addresses to forward frames within a local network (LAN).
Switches create and maintain MAC address tables to make forwarding decisions.
Examples of switches include Ethernet switches and VLAN switches.
Layer 3 (Network Layer):
Some advanced switches (known as Layer 3 switches) can perform routing functions.
Layer 3 switches can route traffic between different subnets within the same LAN.
They use IP addresses to make routing decisions.
Layer 3 switches combine the features of switches and routers.

Tailgating is when someone follows an authorized person into a restricted area without having the proper credentials. This is usually done by pretending to be with the authorized person, or by offering assistance. Tailgating is a social engineering attack and does not require any technical skill.

An Independent Basic Service Set (IBSS) is a type of wireless network that does not require an access point or a wired network. An IBSS allows wireless devices to communicate directly with each other using ad hoc mode. An IBSS is also known as an ad hoc network or a peer-to-peer network. A network technician can configure an IBSS to connect two laptops together and transfer files.

The OSI model is a conceptual framework that divides the network communication process into seven layers, each with a specific function and protocol4.
The session layer is the fifth layer of the OSI model, and it is responsible for establishing, maintaining, and terminating sessions between applications on different devices45.
A session is a logical connection that allows two or more applications to exchange data for a certain period of time5.
For example, when two users on a LAN establish a video call, the session layer coordinates the initiation, synchronization, and termination of the call, using protocols such as SIP (Session Initiation Protocol) or H.32356.
The session layer also provides services such as authentication, authorization, encryption, and checkpointing5.
The other layers of the OSI model have different roles in the network communication process, such as:
The physical layer is the first layer, and it is responsible for transmitting and receiving bits over a physical medium, such as a cable or a wireless signal4.
The transport layer is the fourth layer, and it is responsible for ensuring reliable and error-free data transfer between devices, using protocols such as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol)4.
The data link layer is the second layer, and it is responsible for framing and addressing data packets over a local network, using protocols such as Ethernet or Wi-Fi4. Reference:
4: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 1: Introduction to Networks, pp. 22-29
5: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 11: Network Services, pp. 443-444
6: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 11: Network Services, p. 452

OSPF stands for Open Shortest Path First, which is a link-state routing protocol that is hierarchal by nature and uses the router ID to control convergence. OSPF divides a large network into areas, which are logical groupings of routers that share the same topology information. Each area has a unique identifier and a designated router that connects it to the backbone area (area 0). OSPF uses the router ID, which is a 32-bit number that uniquely identifies each router in the network, to establish adjacencies and exchange routing information. OSPF also uses the router ID to break ties when choosing the best path to a destination. OSPF converges faster than distance-vector routing protocols such as RIP and EIGRP, as it uses the Dijkstra algorithm to calculate the shortest path based on the link cost. BGP, on the other hand, is a path-vector routing protocol that is used to exchange routing information between autonomous systems on the Internet. BGP does not use the router ID to control convergence, but rather uses attributes such as AS path, local preference, and MED to select the best route. BGP is not hierarchal by nature, as it does not divide the network into areas, but rather uses prefixes and policies to control the routing behavior.
Reference
1: OSPF - N10-008 CompTIA Network+ : 2.1
2: CompTIA Network+ N10-008 Certification Study Guide, page 146-149
3: CompTIA Network+ N10-008 Exam Subnetting Quiz, question 19
4: CompTIA Network+ N10-008 Certification Practice Test, question 8