Network Engineer Interview Questions
PART 1 | PART 2 | PART3 | PART4
click on the questions to get answers
- User(s) are complaining of delays when using the network. What would you do?
- Name some of the ways of combining TCP/IP traffic and SNA traffic over the same link.
- What sort of cabling is suitable for Fast Ethernet protocols?
- What is a Class D IP address?
- What is Firewall?
- How do I monitor the activity of sockets?
- How would I put my socket in non-blocking mode?
- What are RAW sockets?
- What is the role of TCP protocol and IP protocol.
- What is UDP?
- How can I make my server a daemon?
- How should I choose a port number for my server?
- Layers in TCP/IP?
- How can I be sure that a UDP message is received?
- How to get IP header of a UDP message?
- Writing UDP/SOCK_DGRAM applications
- How many bytes in an IPX network address?
- What is the difference between MUTEX and Semaphore?
- What is priority inversion?
- Different Solutions to dining philosophers problem.
- What is a message queue?
- Questions on Shared Memory.
- What is DHCP?
- Working of ping, telnet, gopher.
- Can I connect two computers to internet using same line ?
- Name some Routing Protocols
- Explain Kerberos Protocol ?
- Difference between discretionary access control and mandatory access control?
- Explain how traceroute, ping, and tcpdump work and what they are used for?
- Describe what a VPN is and how it works?
- Describe the commands to set up a route.
- How do you display a routing table?
- What is a route flap?
- What is a metric?
- When do you use BGP, IGRP, OSPF, Static Routes?
- What do you see as current networking security issues (e.g. NFS mounting, spoofing, one time passwords, etc.)?
- Describe a routing filter and what it does.
- Describe an access list and what it does.
- What is a network management system?
- Describe how SNMP works.
- Describe the working environment you are currently in, e.g. frequent interruptions, frequent priority shifting, team or individual.
- What do you use to write documentation? Editor? Mail reader?
- What platform (s) do you currently work on at your desk?
- How do you manage multiple concurrent high level projects?
- Describe a recent short term stressful situation and how you managed it.
- How do you manage a long term demanding stressful work environment?
- Have you worked in an assignment based environment, e.g. work request/trouble ticket system, and if so, describe that environment.
- Describe what network statistics or measurement tools you are familiar with and how you have used them.
- Describe what a VPN is and how it works.
- Describe how VoIP works.
- Describe methods of QoS.
- How does ToS bit work?
ANSWERS
Answer:User(s) are complaining of delays when using the network. What would you do?
There are lot of concerns that cause network delays, The Administrator / Network Enginrer must check the following simple tasks before he / she proceed.
Answer:
Name some of the ways of combining TCP/IP traffic and SNA traffic over the same link.
Answer:
What sort of cabling is suitable for Fast Ethernet protocols?
Answer:
What is a Class D IP address?
Class D IP Address is iused in Internet Protocol version 4 (IPv4), Class D IP address beginning with a binary 1110. Class D addresses are reserved for multicast applications only.
| Class | Leading bitts | Start IP | End IP | Default SNM |
| Class D | 1110 | 224.0.0.0 | 239.255.255.255 | NA |
Bit-wise representation
Class D
224. 0. 0. 0 = 11100000.00000000.00000000.00000000
239.255.255.255 = 11101111.11111111.11111111.11111111
1110XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX
Answer:
What is Firewall?
A firewall is a secure and trusted machine that sits between a private network and a public network. The firewall machine is configured with a set of rules that determine which network traffic will be allowed to pass and which will be blocked or refused. In some large organizations, you may even find a firewall located inside their corporate network to segregate sensitive areas of the organization from other employees. Many cases of computer crime occur from within an organization, not just from outside.
I have a nice article on firewall in my website take a look here
Answer:
How do I monitor the activity of sockets?
You can use Microsofts packet monitor software here for network activity events, or Microsoft's NetMon. If you want to use some free 3rd party softwares like; nirsofts Socket Sniffer small but yet powerful and free...
Answer:
What are RAW sockets?
A Raw Sockets or R-Sockets is a socket that allows access to packet headers on incoming and outgoing packets. Raw sockets always receive the packets with the packet header included.
Answer:
What is the role of TCP protocol and IP protocol.
The role of tcp is to the data form one machine to another machine in network. and the role of ip is to idenfify the machine in the network.
Answer:
What is UDP?
User Datagram Protocol or UDP is part of the Internet Protocol suite, using which, programs running on different computers on a network can send short messages known as Datagrams to one another. UDP can be used in networks where TCP is traditionally used, but unlike TCP, it does not guarantee reliability or the right sequencing of data. Datagrams may go missing without notice, or arrive in a different order from the one in which they were sent.
Answer:
Layers in TCP/IP?
Not to Confuse between OSI layers and TCP/IP layers. for OSI Models I have a article here
Answer:
How can I be sure that a UDP message is received?
UDP stands for: User Datagram Protocol, is connectionless and unreliable. Its also called connectionless Protocol. The packets sent using UDP can go missing without senders information, but It is very fast compared to other methods, which is why it is used, there is no acknowledgement sent back to the source to let it know everything arrived ok.
take a look @ UDP article in my site here.
Answer:
How to get IP header of a UDP message?
Answer:
How many bytes in an IPX network address?
An IPX address uses 80 bits, or 10 bytes, of data. The first four bytes show the network address, and the last six bytes always represent the node address, which is the MAC address. An example is 00007C80.0000.8609.33E9. The first eight hex digits (00007C80) represent the network portion of the address.
Answer:
What is the difference between MUTEX and Semaphore?
The Differece is, MUTEX will only let its owner a access, While Semaphore can allow number of "UNKNOWN" Access.
Answer:
What is priority inversion?
Priority inversion is a situation where in lower priority tasks will run blocking higher priority tasks waiting for resource.
Answer:
What is DHCP?
Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers configured for a given network.
Answer:
Name some routing protocols
- RIP(ROUTING INFORMATION PROTOCOL)
- IGRP( INTERIOR GATEWAY ROUTING PROTOCOL)
- EIGRP(ENHANCED INTERIOR GATEWAY ROUTING PROTOCOL)
- OSPF (OPEN SHORTEST PATH FIRST)
- BGP( BORDER GATEWAY PROTOCOL)
Answer:
Explain Kerberos Protocol ?
Kerberos is an authentication protocol that has become very popular .three server are involved in the karberos protocol. Authentication server(AS),ticket granting Server(TGS),real server.
Answer:
Difference between Discretionary Access Control(DAC) and Mandatory Access Control(MAC)?
DAC is used by itself according to it it is access and comtrolled while mas it has to be compulsory give the access controll.
MAC is designed and enforced in the initial stages and can not be changed by entity; from a laymen angle: OS writing to BIOS is not allowed.
DAC is designed in such a way that access shall be granted based on the discretion; ex. database table access.
Answer:
Explain how traceroute, ping, and tcpdump work and what they are used for?
traceroute, ping, and tcpdump test the connectivity of the detination in question by sending ICMP packets and checking the responce(TTL) which is the routers encountered in the path.They are used to check the connectivity and the distance to the destination.
Answer:
Describe what a VPN is and how it works?
VPN Virtual Private Network, A service which provides Secure network connectivity between two remote locations over a insecure network(internet/ISP).
Answer:
How do you display a routing table?
The function and syntax of the Windows ROUTE command is similar to the Unix or Linux route command. Use the command to manually configure the routes in the routing table.
Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.
C:\Documents and Settings\Administrator>route print
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x1000003 ...00 19 d1 67 d2 f3 ...... Intel(R) PRO/100 VE Network
Connection (Microsoft's Packet Scheduler)
===========================================================================
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.69 1
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.1.0 255.255.255.0 192.168.1.69 192.168.1.69 1
192.168.1.69 255.255.255.255 127.0.0.1 127.0.0.1 1
192.168.1.255 255.255.255.255 192.168.1.69 192.168.1.69 1
224.0.0.0 224.0.0.0 192.168.1.69 192.168.1.69 1
255.255.255.255 255.255.255.255 192.168.1.69 192.168.1.69 1
Default Gateway: 192.168.1.1
===========================================================================
Persistent Routes:
None
Answer:
What is a route flap?
In computer networking and telecommunications, route flapping occurs when a router alternately advertises a destination network via one route then another (or as unavailable, and then available again) in quick sequence. A closely related term is interface flapping where an interface on a router has a hardware failure that will cause the router to announce it alternately as "up" and "down".
Answer:
What is a metric?
Metrics is a property of a route in computer networking, consisting of any value used by routing algorithms to determine whether one route should perform better than another (the route with the lowest metric is the preferred route). The routing table stores only the best possible routes, while link-state or topological databases may store all other information as well. For example, Routing Information Protocol uses hopcount (number of hops) to determine the best possible route.
A Metric can include:
- number of hops (hop count)
- speed of the path
- latency (delay)
- path reliability
- path bandwidth
- load
- MTU
In EIGRP, metrics is represented by an integer from 0 to 4294967295. In Microsoft Windows XP routing it ranges from 1 to 9999.
Source: http://en.wikipedia.org/wiki/Metrics_(networking)
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