9 Apr, 2007
Networking Interview Questions
- What is required to support full-duplex Ethernet?
* Multiple paths between multiple stations on a link
* Automatic sensing operation by all connected stations
* Loopback and collision detection disabled
* Full-duplex NIC cards
Correct answer: C D
Full duplex ethernet requires that the NIC supports full-duplex, and loopback and collision detection are disabled.
- Which layer is responsible for determining if sufficient resources for the intended communication exists?
* Application
* Network
* Session
* Presentation
* Transport
Correct answer: A
The Application layer is responsible for determining if sufficient resources for the intended communication exists.
- What are the 2 functions of the Data Link Mac layer?
* Handles access to shared media
* Manages protocol access to the physical network medium
* Provides SAPs for higher level protocols
* Allows multiple devices to uniquely identify one another on the data link layer
Correct answer: B D
Media Access Control (MAC) -The MAC sublayer manages protocol access to the physical network medium. The IEEE MAC specification defines MAC addresses, which allow multiple devices to uniquely identify one another at the data link layer.
- Describe End to End network services: (Choose all that apply)
* Best Route selection
* Accomplished Segment by Segment, each segment is autonomous
* Flow Control & Data Integrity
* Best efforts packet delivery
Correct answer: A B C D
All of the above End to End network services.
- Which of the following provide correct information about a protocol at the transport layer of the OSI model?
* UDP - Provides Connectionless datagrams service
* TCP - Provides Connection Oriented Services
* SMTP - Provides Mail Exchange
* IP - Route determination
* TCP - Provides Flow Control and Error Checking
* FTP - Transfers of Files
Correct answer: A B E
Only TCP and UDP work at the Transport layer of the above choices. IP is a Network layer protocol. SMTP and FTP are application layer protocols.
- Which protocol works at the Internet layer and is responsible for making routing decisions?
* UDP
* IP
* TCP
* ARP
Correct answer: B
Internet Protocol - IP provides routing and a single interface to the upper layers. No upper layer protocol and now lower layer protocol have any functions relating to routing. IP receives segments from the transport layer and fragments them into packets including the hosts IP address.
- Which layer is responsible for providing mechanisms for multiplexing upper-layer application, session establishment, and tear down of virtual circuits?
* Session
* Network
* Physical
* Transport
* Application
* Presentation
Correct answer: D
The Transport layer does the following: Responsible for end-to-end integrity of data transmission. Handles multiplexing upper-layer application, session establishment and tear down of virtual circuits. Hides details of network dependent info from the higher layers by providing transparent data transfer. The ‘windows’ works at this level to control how much information is transferred before an acknowledgement is required.
- Which of the following are logged when IP access list logging is enabled?
* source address
* protocol
* source port
* destination address
* access list number
* destination port
Correct answer: A B C D E F
All of the above are logged when IP access list logging is enabled.
- What’s the default CDP holdtime in seconds for Cisco routers?
* 30 seconds
* 180 seconds
* 90 seconds
* 60 seconds
Correct answer: B
Cisco Discovery Protocol is a proprietary protocol to allow you to access configuration information on other routers and switches with a single command. It uses SNAP at the Data-Link Layer. By default CDP sends out a broadcast every 60 seconds and it holds this information for 180 seconds. CDP is enabled by default.
- Which two of the following protocols are used at the Transport layer?
* ARP
* UDP
* ICMP
* RARP
* TCP
* BootP
Correct answer: B E
TCP and UDP operate at the Transport layer.
- LAN stands for which of the following?
* Local Area Network
* Local Arena Network
* Local Area News
* Logical Area Network
Correct answer: A
LAN stands for Local Area Network
- Choose three reasons why the networking industry uses a layered model:
* It facilitates systematic troubleshooting
* It allows changes in one layer to occur without changing other layers
* It allows changes to occur in all layers when changing one protocol
* It clarifies how to do it rather than what general function to be done
* It clarifies what general function is to be done rather than how to do it
Correct answer: A B E
Why do we have a Layered Model?
1) It reduces complexity
2) Allows for a standardized interface
3) Facilitates modular engineering
4) Ensures interoperable technology
5) Accelerates evolution
6) Simplifies teaching and learning
- Which layer is responsible for identifying and establishing the availability of the intended communication partner?
* Application
* Presentation
* Transport
* Session
* Network
Correct answer: A
The Application layer performs the following: Synchronizing sending and receiving applications. Program-to program communication. Identify and establish the availability of the intended communication partner, and determine if sufficient resources exist for the communication. Popular application protocols include WWW, SMTP, EDI, FTP, Telnet, and SNMP
