Most common latest interview questions with answers (2010/2011)
(Technical questions expected in all interviews – for system admin/ IT administrator and other jobs related to IT networking)
1. Port number for SMTP? The answer is port number 25.
One of the most common interview questions is SMTP port number. As per my experience most of the interviewers asked me the same (May be the first question). Everyone wonder how this question related to the job. But this question is testing your experience with firewall. How? Because every company uses some kind of mail server (Exchange or other mail server), in order to allow the messaging communication between internal company to external world, this port number plays important role. So everybody must aware of this question.
2. What does ARP do? – ARP used to map IP address to respective MAC address.
This looks very simple, but many people answered wrongly. Most of answer would be ‘ARP converts IP to MAC’ which is completely wrong. So think twice before answer this question. Why? Answer is in next.
3. What is DNS? (Forward DNS and reverse DNS) – DNS (Domain Naming Service) which translates host name to IP. Host name could be URL, domain name or FQDN (Fully Qualified Domain Name) of any physical/virtual machine. Reverse DNS translates IP to hostname.
Here is confusion between DNS and ARP. ARP is a layer 2 protocol which deals with Data link layer characteristics (Ex. MAC address). DNS is layer 7 application protocol, only deals with configured information in application (Ex deals with DNS SERVER).
4. Another port number question: what is the port number for SSH? Answer is 22.
Be careful when answering this question, the interviewer may confuse you with HTTPs port number (443). We might think the answer may be 443, because both port numbers are using secure connection. HTTPs is for secure connection to the website where as SSH provides secure channel (secure communication and file transfer) between two points in network.
5. Port number for FTP – 20 and 21. 20 for data 21 for control
6. What is command to view IP details in windows machine and Linux machine?
IPconfig – command for listing all interface details in windows and ‘ifconfig’ for linux.
7. What are commands associated with IPCONFIG command?
Ipconfig/release
Ipconfig/renew
Ipconfig/flushdns
8. What is network gateway?
Network gateway is the entry or exit point for any network and connects two different networks. This gateway can be either hardware based or software based or both.
9. What is subnet mask?
Subnet mask is used to identify network address and host address. In other words it separates network and host ID from IP address.