OSI Model Interview Questions for CCNA

 

A Server at a company called NETWORKWALKS is using TCP/IP protocol to connect to the Network & is running multiple applications. At which layer of OSI Model is this Server operating?

This Server is operating at Application Layer of OSI Model

 

What are LLC and MAC sublayers? What are their functions?

LLC & MAC Sublayers are the two sub-divisions of Data link layer (Layer 2) of the OSI model.

1.    Media Access Control (MAC) sublayer controls device interaction

2.    Logical Link Control (LLC) sublayer controls LLC sublayer deals with addressing and multiplexing

 

Which Layer is used to deal with mechanical and electrical specifications?

Physical Layer is used to deal with mechanical and electrical specifications

 

What are the functions of LLC (Logical Link Control) Sub-Layer?

LLC sublayer is primarily concerned with multiplexing protocols to be sent over MAC sublayer. LLC sublayer does this by splitting up the data to be sent into smaller frames and adding descriptive information to these frames, called headers.

 

What are the functions of MAC (Media Access Control) Sub-Layer?

Media Access Control Layer controls how a computer on the network gains access to the data and permission to transmit it. It is also responsible for the actual access to the network cable, or communication medium.

 

Segmentation and reassembly is responsibility of which layer of OSI Model?

It is responsibility of Layer-4 (Transport Layer) of OSI Model

 

Which layer is present in OSI Model & is not present in TCP/IP model?

Session layer is present in OSI Model (not found in TCP/IP model layer)

 

What are the main functions of Physical Layer of OSI Model?

Below are the functions & responsibilities of Physical layer of OSI Model:

·         Real data delivery of bits.

·         Physical medium standards & their technical specifications like signal levels, impedance, Optical levels, Bandwidth & frequency.

·         Physical network topology specifications (e.g. Bus, Ring, Mesh or Star network)

·         Bit synchronization for serial communications

·         Layer 1 Flow Control to match sender/receiver rates

·         Start/Stop Signalling , Circuit Switching and L1 Multiplexing which is used in SDH, DWDM & OTN

 

Which Network equipment belong to Physical Layer of OSI Model?

Below network equipment belong to Physical Layer of OSI Model:

·         Hubs

·         Repeaters

·         NIC (Network Interface Cards)

·         Modems

·         Media Convertors

·         Ethernet Cables

·         Optical Fibers

·         Patch Panels

 

Which networking protocols belong to Physical Layer of OSI Model?

Important Protocols at Physical Layer include WiFi, USB, Bluetooth , RJ45, SDH, DWDM, OTN, MW, RS232, ATM & DSL

 

What are the functions & duties of Data Link Layer?

Below are the functions & responsibilities of Data Link Layer of OSI Model:

·         L2 Switching: Process & filter incoming frames & send them to their desired destination

·         Logical Link Control: Establish and control the logical links between local devices on a network & frame Sync

·         Media Access Control: It controls the access to Media by devices

·         Physical Addressing: It assigns a unique ID to devices on Layer2 Network such as Ethernet called MAC Address

·         Encapsulation: Network layer data packets encapsulation into frames & reverse Decapsulation

·         Error Control: Is uses error control mechanisms such as CRC to ensure reliable delivery of data

·         Flow Control: It implements flow control mechanisms to control sender/receiver transmission rates

·         Loops control: Layer2 Loop Control by using protocols like STP

 

Which Network equipment belong to Data Link Layer of OSI Model?

Equipment operating at Data Link Layer include L2 Switches, Bridges, Access Points, Modems & NIC

 

Which networking protocols belong to Data Link Layer of OSI Model?

Below are the important protocols at Data Link Layer of OSI Model:

·         Ethernet

·         HDLC

·         ARP

·         PPP

·         Frame Relay

·         VLAN

·         STP

·         L2 QoS

·         LLDP

·         CDP (Cisco Discovery Protocol), L2TP, NDP, VTP, MAC)

 

What are the functions & duties of Network Layer?

Network Layer performs important functions like Logical Addressing, Routing, Encapsulation, Fragmentation & Error Control

 

Which Network equipment belong to Network Layer of OSI Model?

Routers and Layer 3 Switches belong to Network Layer of OSI Model

 

Which networking protocols belong to Network Layer of OSI Model?

Important Protocols at Network Layer include IPv4, IPv6, RIP, OSPF, BGP, ICMP, EIGRP, IPSec, IPX, NAT, GRE, HSRP and VRRP

 

What are the functions & duties of Transport Layer?

Transport Layer performs important functions like L4 Addressing, Multiplexing/De-multiplexing, Sequencing, Error Control, E2E Connection Mgmt, Transmission,  Segmentation and Flow Control

 

Which Network equipment belong to Transport Layer of OSI Model?

Equipment operating at Transport Layer include Firewalls, Gateways and Load Balancers

 

Which networking protocols belong to Transport Layer of OSI Model?

Important Protocols at Transport Layer include TCP, UDP, SPX, BGP, ESP, Fiber Channel Protocol, iSCSI & SCTP

 

What are the functions & duties of Session Layer of OSI Model?

Session Layer performs important functions like Sessions Management, Authentication, Authorization, Duplex Control

 

Which Network equipment belong to Session Layer of OSI Model?

Important Protocols at Session Layer include SIP, PPTP, H.245, PPTP/L2TP, SMB, NFS and PAP

 

Which networking protocols belong to Session Layer of OSI Model?

Equipment operating at Session Layer include Firewalls, Gateways, Load Balancers and Computers

 

What are the functions & duties of Presentation Layer?

Presentation Layer performs important functions like Data Formatting, Data Representation, Data Encryption/Decryption, Data Compression/De-compression

 

Which Network equipment belong to Presentation Layer of OSI Model?

Important Protocols at Presentation Layer include ASCII, EBCDIC, JPEG, MPEG, GIF, PNG, TIFF, SSL and TLS

 

Which networking protocols belong to Presentation Layer of OSI Model?

Equipment operating at Presentation Layer include Firewalls, Gateways, Load Balancers & Computers

 

What are the functions & duties of Application Layer?

Below are the functions & responsibilities of Application Layer of OSI Model:

·         Applications Management: Manages applications software running on a computer or terminal

·         End User Processes Management: Application Layer is also responsible for End User Processes Management

·         Supply Network services to Apps: Supplies Network Services to End User Applications

Application Layer also provides miscellaneous other services including Naming Services (e.g. DNS), Mail Services (e.g. SMTP/POP3), Remote Login Services (e.g. Telnet/SSH), Remote Host Mgmt (e.g. SNMP),…

 

Which Network equipment belong to Application Layer of OSI Model?

Below network equipment belong to Application Layer of OSI Model:

·         Firewalls

·         Gateways

·         End Devices e.g. Computers, Smart Phones, Servers, …

·         Devices that inspect & balance application traffic e.g. Proxies, Firewalls, Load Balancers …

 

Which networking protocols belong to Application Layer of OSI Model?

Below are the important protocols at Application Layer of OSI Model:

·         HTTP (Hypertext Transfer Protocol)

·         DNS (Domain Name System)

·         DHCP

·         FTP (File Transfer Protocol)

·         Telnet

·         POP3/IMAP

·         BOOTP (Bootstrap Protocol)

·         Bitcoin