What is the difference between a hub, a switch, and a router?

A hub is a small, simple, low-priced device that joins multiple computers together. A switch is a small hardware device that joins multiple computers together within one local area network (LAN) and they operate at layer 2 of the OSI model. Routers are the physical devices that join multiple wired or wireless networks together and they operate at layer 3 of OSI model.

What meaning has ICMP?

The Internet Control Message Protocol or ICMP is belonging to the TCP/IP set and has the role of testing the notifications transmissions of hosts and gateways and manages the messages of error and control.

How is UDP different from TCP?

While TCP is a network protocol that is based on connection, UDP is not connection-based. Connection means that the transfer of data between two points on a network is made with the acknowledgment of the success of the process. TCP is used if we want to transfer data and receive confirmation that the data was really sent, no matter in what time period it was made. For example, UDP is used when a movie is streamed and we need continuous frame play without interruptions.

What was the strangest situation that you had to deal with regarding managing a network?

The candidate will answer this question by mentioning an experience in which he/she had difficulties being understood by the other workers in the company and his/her suggestions were not followed as they were explained, leading to a network failure or other severe problems.

Please tell us some job-specific tasks that you have performed in your previous organization?

The profession-specific tasks that I have performed include installing the original, new version software, keeping record of all the changes to the network environment, managing the local area network, and providing backup. I had also supervised all the activities on the network and developed management information solutions by using business objects.

What are your technical and non-technical skills?

Well, I have 8 years of experience as a network manager. During the entire course of my profession, I have acquired various technical and non-technical skills. I have gained good logical and technical knowledge of networking and software. I have intensive knowledge of Oracle database systems, design, crystal reports and .NET. Apart from this, I have excellent communication and interpersonal skills and I have the ability to function successfully in both team and independent work environments.

How a network maintenance operation is made?

The maintenance of a network is made by running tests for the purpose of detecting viruses, breakdowns, hackers or bugs. A network administrator should always stay updated with the latest technology and this can be made only through constant market research. Staying up-to-date helps the administrator to improve the network and to maintain it in a good state all the time.

Which are, in your opinion the best traits of a network administrator?

The guys that are involved in network administration in most cases they are natural fixers, they were passionate about computers since they were kids and they know when a problem appears before it makes much damage, they are able to prevent it so it is not necessary to repair it.

How can you explain the meaning of a Remote Procedure Call or RPC?

A Remote Procedure Call makes the complexity of the network hidden. It actually invokes a remote server function and closes itself until the results come back. This process is a synchronous one.

What is the meaning of Middleware?

For good communication between servers and clients, there is a software called Middleware. Its behavior is just like the one of a bridge. The application from the client calls a service and Middleware manages the transfer through the network and receiving results. Middleware doesn’t contain any additional software, the other applications are found on the server or on the client.

Do you difficult for a network administrator to stay so much in front of the computer?

When a person decides to become a network administrator he/she must be aware that physical effort will not take part of the job and even if it is, on rare occasions, it is minimal. The work of a network administrator resumes to doing different tasks on the computer and giving phone calls for support. On rare occasions, he may act as a system administrator but this is due to urgency.

What is an object server doing?

With the aid of an object server, the application from the client or from the server is a group of communicating objects. The Objects Request Broker or ORB facilitates the communication between client objects and server objects.

What is the difference between these three: encryption, encoding, and hashing?

Encryption is used for keeping data intact and safe and is not so easy to reverse because it requires a certain key. Encoding is used to protect data as it passed through the network and after reaching the destination the data returns to the initial state because it is easily reversible process; being easy reversible makes it not so good for data protection. Hashing is a protection method that is not reversible and the data comes under the form of a string named the hash value.

How can we explain the following terms: gateway and router?

A gateway is like a door that opens for a data package to exit the interior network and step outside the network. The Router handles the transportation of data packages over the interior network.

What is the way in which the Asynchronous Transfer Mode works?

The Asynchronous Transfer Mode or ATM is a connection technology that works by transmitting data into organized 53 bytes (small) packages through a physical environment with a high efficiency. Packing data into small cells reduces transportation delay so the speeds reached by this technology are very high; it can reach even 10 Gb per second.

What types of Transmission media do exist?

The signals transported through Transmission media care have two types:

Guided media

Guided media are the conduit types that allow transmission through coaxial cables, fiber optics, and twisted pairs. In this type of transmission, the data flow is dependable on the physical limits of the conducting material. The signal is transported over the metallic conductor like an electric current, this is the case for coaxial cables and twisted pairs. In the case of fiber optics, lights signals are transmitted through a plastics or glass cable.

Unguided media

This type refers to wireless communication which uses the air to propagate the signal, along with cellular phone technology, satellite technology, and radio technology. The signal takes the form of electromagnetic waves and travels on the air without the need of a solid conductor.

What is a broadcast storm?

We say we have a broadcast storm when the traffic or broadcasting on the network has reached certain limits, meaning that it’s overwhelmed and this can make the network lose the connection. In order for the network to be protected against broadcast storm a firewall must be installed.

How can we explain what a Protocol Data Unit is?

The Protocol Data Unit or PDU is the data unit from the LLC level and has four fields:

a) the source service access point or SSAP
b) the destination service access point or DSAP
c) the information field
d) the control field

The first two are used for finding the protocol stacks by the LLC on the machines that send or receive data, they are addressed. The control field states when a PDU frame is a supervisory or an information frame.

What difference there is between these terms: RARP and ARP?

RARP or the reverse address protocol determines a host to find the internet address when only a physical address is known. ARP or the address resolution protocol brings together the IP address which is 32 bit with the physical address which is 48 bit. It is used for finding the physical address when the IP is known.

What is the meaning of FTP and TFTP application layer protocols?

FTP or File Transfer Protocol is the process file transfer between hosts and it’s provided by the TCP/IP. Two connections are made that are secure over the TCP: one for file copying and one for information control. These connections are also called virtual circuits. TFTP or the Trivial Transfer Protocol is using UDP to transfer files from a remote host to a local host but without the advantages of security and reliability.

Can you give me a list of priorities concerning network support?

Usually, a network administrator doesn’t receive a single call when a problem arises. The problems in most cases affect multiple employees so we must learn how to make a list of priorities. The major problems that we must take into consideration are the following:

a) Minor problem- these come from a single user and happen quite often, the user can continue working but with some lacks.
b) Partial failure of a workstation- in this case a single user is affected and almost all the tasks are compromised
c) Small failure of a network- this affects a group of users, not just an individual
d) Partial failure of a network- this has an impact on multiple user groups
e) Total failure of a workstation- in this case an individual can’t work at all
f) Total failure of a network- when everybody gets the problem and nothing works.

Which are the tools you carry usually for troubleshooting?

A generic question from the interviewer that wants to verify if the flow of the answer remains the same no matter what question is asked, so the details of the answer are not the ones that really count here. The “gear “ of a network admin must include CD-ROM’s, technical support links, networks analyzers, server log files, telephone numbers, README files and so on. Subscriptions to certain support companies are important to be declared.