Networking Engineer Interview Quesitons

Q1- What is different between Router and Bridge ?
Ans-

Q2-   What are the memories in  Router and what are their uses ?

Ans-

    

Flash Memory-   It is used to store IOS images in Router.

DRAM-               It stores running information in Router. It stores all unsaved settings while router is                             ON. It is a type of volatile memory where data is saved till power is ON.

NVRAM-           NVRAM stands for Non-Volatile RAM . It stores saved settings . It is used when                                router is started. After IOS loading startup configurations are loaded from NVRAM.

ROM-               It stores mini IOS, configuration registers value and responsible for POST and IOS                               booting.

Q3-  What is Telnet ?

Ans-     Telnet is application layer protocol which is used for remote management. Using this protocol we can access command console of networking devices and can make changes in their settings. We can access  PC, Router, Switch and Servers using telnet.

It uses TCP port number 23.

Q4- What are the data transmission modes ?

Ans-  There are three type of transmission modes

  Simplex-  It is an oneway communication where only one device can send data and other will recieve  data. This type of transmission is done through a single thread of fiber optic cable. That is why we use pair of Fiber Optic Cable . One is for send and another is for recieve.

 Half Duplex-  

  In this type of transmission both devices can send or recieve data but not at a time. Both devices will be able to send or recieve data one by one. If first device is sending data then second device will wait untill  first device's transmission complete.  Example of halfduplex transmission medium is coaxial cable.

Full Duplex-

In this type of transmission both devices can send or recieve data at a time.Today's Fast Ethernet or Gigabit Ethernet is based on full duplex. We can create full duplex network by using Twisted pair Cable or pair of Fibler Optic Cable.

Q5- What is Ethernet ?

Ans- Ethernet is a LAN standard given by IEEE. It is a most popular standard where data transmission rate is 10 mbps and data is transmitted in frame formate. For addressing of devices in network Ethernet Address (MAC address) is used. There are some advance version of Ethernet --

Fast Ethernet ( 100 Mbps) full duplex

Gigabit Ethernet (1Gbps)   full duplex

10 Gigabit Ethernet (10Gbps) full duplex

40 Gigabit Ethernet (40 Gbps) full duplex

Q6-What is different between .pst and .ost ?

Ans-  .pst and .ost both are the file extension of microsoft outlook data file. These files contains user's mail. There are two protocols to recieve mails from mail server. 1st is POP and 2nd is IMAP. If we configure email client in automatic mode (smartphones or PC) It automatically configured by using IMAP.

 If we configure manually then we can choose POP or IMAP. IMAP does not store data permanently and always access data from mail server when we sync.It does not download attachments automatically on email client computer . It is good for multidivice configuration because all devices works online and sync to each other. When we use IMAP then .ost file is create for mail storage.

When mail is confugured using POP then .pst file is created to store mail. This files contains all inforamation permanently on email client computer. All attchements are downloaded on email client automatically. POP is most used protocol for PCs. We can see all previous mails and can open all attachments even when PC is offline.

Q7- What information should we have to configure outlook (Email Client) in a PC.

Ans-  We should have some inforamtion related to email account which are-

 1-Email ID

 2-Password

 3-Incomming mail server name or Address (POP or IMAP server)

 4-Outgoing mail server name or Address ( SMTP server)

 5-Port number for incomming and outgoing mail servers (POP-995,SMTP-465/587, IMAP-993)

  

These port numbers are with SSL because most of mails servers are supporting only ssl/tls connection. Which secures connection by encrypting data between mail server and clients.

Q8- Tell me five email clients name ?

Ans-  Microsoft -   Outook

          IBM         -    Lotous Notes

          Mozilla    -    Thunderbird

          Apple       -    Apple Mail

           Mail bird -     Mail bird

    

TRANSMISSION MEDIA

There are two type of transmisson media-

1- Guided media (Cable)

2- Unguided media (wireless)

Guided Media-   Guided media is a type of data transmission medium which is guided by administrator. Administrator decides a way for data transmission. Where we need to install PC we can install cable for this.

Three types of cables are used for networking-

1-  Coaxial Cable

2- Twisted Pair Cable

3- Fiber Optic Cable

Coaxial Cable- It is a copper cable which works on half duplex . It is used in linear bus topology for                                networking.It can transfer data one PCs data at a time. Now days it used for distributing TV cable connection. There is only one way of data transmission. Service providers broadcast signals and TV receiver receives signal.Coaxial cable uses BNC connector such as BNC terminator, BNC Cable connector, BNC T type connector.

It is two type -

Thick coaxial (Thicknet/RG8)-   It is a type of coaxial cable which is used as a backbone cable in Bus topology.

Speed                               = 10mbps

Duplex                             = Half

Segment length                = 500 miter

Interferance                      = More secure transmission. It is shielded by PVC and mesh.

Crosstalk                           = Less chances of cross talk because it is shielded.

Thin Coaxial Cable (Thinnet/RG58)-  It is thinner than thick net . It is easy to install.

Speed                                =10 mbps

Duplex                              =Half

Segment lengh                  = 200 miter ( practicaly 185 miter)

Twisted Pair Cable-- 

It is most commonly used LAN cable . It is a type of cable which consist of  8 cylindrical wires. It is two type -

1-   UTP ( Unshielded Twisted Pair)  Cable- 

This types of cables don't  have shielding like STP cables. These cables have 8 wires covered with PVC and Outer jacket. These are widely used in LAN network because of some features-

1- Easy to install
2-Cheaper than other cables
3- Better speed
4- Good for full duplex star network

2-   STP ( Shielded Twisted Pair ) Cable 

These type of cables are same as UTP but they have shielding to protect from EMI, RFI and cross talk. They also have 8 wire and uses RJ45 connector. These are used where electrical noise is more.

Fiber Optic Cable- 

As name suggests it is made up of fiber and it's core is made up of soft glass. It uses laser or led for data transmission that is why it is known as optical cable. It provides best transmission speed and protection from internal or external interference (EMI, RFI and cross talk) . It is also unaffected by environmental issues. This type of cable is generally used for long distance because this can transmit data to a long distance without attenuation.

It is two type-

1- Single Mode Fiber

2-Multi mode  Fiber

1- Single Mode Fiber-  This type of cable is used for long distance. It uses laser for light source and can transmit one signal at a time. It uses uses always two cable , one for transmit and an other for receive.

Multi mode Fiber optic cable-  Multi mode fibers are used for short length . These type of cables can transmit multiple signal simultaneously . They use led for light source. These are used in a LAN where are more chances of interference . Because they protect from interference. They also use two cable, one for transmission and an other for receiving. 

You can not identify difference  between SMF and MMF by seeing cables. You need to read on cable or packet. because both use these connectors-

SC- Subscriber connector

ST- Straight tip

SMA- Sub miniature

SOME IMPORTANT PROTOCOL AND THEIR WORK

      

 ICMP (Internet Control message Protocol-    port-1 and 7) - For connection      troubleshooting.

 

ARP (Address Resolution Protocol-    port- 219) Used to resolve IP to MAC address.

 

RARP( Reverse Address Resolution Protocol-          port -67 and 68) Used to resolve MAC to IP.

 

DHCP( Dynamic Host Configuration Protocol     port- 67 and 68 ) Used to provide automatic IP address

 

HTTP (Hyper Text Transfer Protocol       port- 80) Used to access web pages from browsers.

 

SMB ( Service Message Block      port- 139) Used to share resources for windows PCs.

 

NFS ( Network File System         port- 111 and 2049 ) Used to share resources between windows and Unix OS.

 

IGMP (Internet Group Message Protocol ) Used to send messages to multiple hosts .

 

SMTP ( Simple Mail Transfer Protocol          port - 25 / SSL-465) Used to send email.

 

POP ( Post Office Protocol                port- 110/ SSL-995)       Used to receive mail

 

IMAP ( Internet Message Access Protocol                 port- 143/ SSL- 993) Used to receive mail.

 

NNTP ( Network News Transfer Protocol            port- 119 / SSL -563 ) Used to send news to a group 

 

NTP( Network Time Protocol             port- 123 ) Used to update time of all network devices.

 

FTP ( File Transfer Protocol            port- 21 and for manage 20) Used to download and upload files in intranet or internet.

 

TFTP ( Trivial File Transfer Protocol        port-   69) Used to download and upload files but less secure than  FTP

 

RDP ( Remote Desktop Protocol               port- 3389 ) Used to access remote desktop

 

TCP ( Transmission Control Protocol )It is a protocol suit which work with another protocols.  Used to deliver data from one device to another .

 

UDP ( User Data gram protocol )It is also a protocol suit which work with another porotcols. Used to deliver data but it is connection less

 

 RIP ( Routing Information Protocol         port- 520) Used for Dynamic Routing.

 

OSPF ( Open Shortest Path First          port- 89 ) Used for Dynamic Routing.

 

BGP ( Border Gateway Protocol          port- 179    ) Used for Routing between two AS.

 

IS-IS ( Intermediate System to Intermediate System         port -2042) Use for routing.

 

PPTP ( Point to Point Tunneling Protocol        port- 1723) Used for tunneling in VPN.

 

L2TP ( Layer 2 Tunneling Protocol          port-500/1701/4500 ) Used for tunneling.

 

SSTP ( Secure Socket Tunneling Protocol        port- 443) Used for tunneling

 

CHAP ( Challenged Handshake Authentication Protocol ) Used for authentication.

 

PPP ( Point to Point Protocol ) It is a point to point serial protocol used in WAN . Used for frmaing.

 

STP (Spanning Tree Protocol ) It is data link layer protocol Used to prevent loop in switches.

 

VTP (Virtual Trunking Protocol )It is data link layer protocol  Used for trunking in switches.