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Thursday, October 5, 2023
COMPUTER NETWORKS - II : TYBCS : SPPU : Internal
Chapter 1: Application Layer
Q. What is DNS?
Answer: DNS, or Domain Name System, is a system that translates human-readable domain names (like www.example.com) into IP addresses, which computers use to identify and locate each other on the internet. It acts as a directory for the internet, making it easier for users to access websites and services using familiar names instead of numerical IP addresses.
Q. What are types of name space?
Answer:
Types of name space are flat name space and hierarchial name space.
Q. Explain flat name space.
Answer: It is a name space where a name is assigned to an address without any structure. It is simply a sequence of characters which may or may not have common section.
Example: URL like google or rediff.
Q. Explain hierarchical name space.
Answer:
It is a namespace where every name is made up of several parts.
Part 1: Defines nature of organization
Part 2: defines name of organization
Part3: Defines departments in organization
These names cannot be duplicated. Example: nirali.com, kthcollege.edu,etc
Q. What is fully qualified and partially qualified domain name.
Answer: If a label is terminated by null string it is called fully qualified domain name and if not terminated by null string then it is called partially qualified domain name.
Q. What is zone transfer?
Answer: A primary server loads info from disk file, and secondary dns server loads info from primary server. When primary dns server downlaods information from secondary one, it is called zone transfer.
Q. What are different sections of domain name space?
Answer: It is divided into three sections:
1) generic domains
2) country domain
3) inverse domain
Q. Explain generic domain.
Answer: It defines registered host according to their generic behaviour.
Generic domains have broader applicability and are not tied to a particular geographic location. Example: .com (commercial), .org (Organizations/ Non-profit ), etc
Q. Explain country domains.
Answer: It uses two character abbreviations (eg: in for India)
Q. What is inverse domain.
Answer: It is used to map the address to a name. Example 121.46.34.132.in-addr.arpa.
Q. What is address resolution.
Answer: Mapping an address to a name is called address resolution.
Q. Define resolver.
Answer: It is a dns client which maps name to an address or address to a name.
Q. What is recursive resolution?
Answer:
1) The client's DNS resolver sends a query to its designated DNS server.
2) The DNS server, if it doesn't have the answer, contacts other DNS servers on behalf of the client, obtaining the answer through multiple steps.
3) The final answer is returned to the client's DNS resolver, which then forwards it to the client. The client's resolver might also cache the answer for future use.
Q. What is Iterative Resolution?
Answer:
Iterative Resolution:
1) The client's DNS resolver sends a query to its designated DNS server.
2) The DNS server, if it doesn't have the answer, returns the best information it has to the client's resolver. It also provides a referral to other DNS servers.
3) The client's resolver continues the process, sending queries to the referred DNS servers step by step, until it obtains the final answer or reaches an authoritative server that provides the required information.
Q. What is cache?
Answer: Whenever a server asks for mapping from another server and receives a response, the DNS stores the information in its cache memory before sending to client.
If same or another client asks for same mapping, it can check its cache memory and give reply.
Q. What are the services provided by user agent? (write any two)
Answer: The services provided by user agent are as follows:
1) Composing Message: It helps user compose or create an email by providing a template on the screen.
2) Reading Messages: It checks each mail and provides one line summary of every received email.
3) Replying to Messages: It allows the user to reply to original sender or to reply all recipients of the messages.
4) Forwarding Messages: It allows the receiver to forward the message with or without extra comments third party.
5) Handling Mail Boxes: It creates two mail boxes, inbox and outbox. Inbox keeps all the received emails until they are deleted by the user and outbox keeps the sent emails until user deletes them.
Q. Write a short note on SMTP.
Answer:
SMTP, or Simple Mail Transfer Protocol, is a standard communication protocol used for sending and relaying electronic mail (email) messages over the internet. It serves as the foundation for the email delivery process, enabling the transfer of messages from a sender's email client to a recipient's mail server. It is a TCP/IP protocol that specifies how computers exchange electronic mail.
Q. What is difference between SMTP, POP and IMAP?
Answer: SMTP is a push protocol which pushes the message from client to server so it is used in first and second stage of mail delivery.
Third stage needs pull protocol from receiver to mail server, so they need MAA (message access agents) which is POP and IMAP. These both retrieve mails at receiver's side.
Q. What is POP3?
Answer: Post office protocol is an application layer internet standard protocol used by local email clients to retrieve email from remote sever over tcp ip connection.
Q. What is IMAP4?
Answer: Internet mail access protocol is similar to POP3 but more compelx and more powerful. It provides following functions:
1) user can check email header before downloading
2) use can search email contents before downloading
3) User can partially download email
4) use can create, delete or rename mailboxes.
5) use can create hierarchy of mailboxes in folder for storage.
Q. Give difference between IMAP4 and POP.
Answer:
Aspect | POP | IMAP |
---|---|---|
Client Support | Typically single client | Supports multiple clients |
Offline Access | Messages accessed offline | Accessible online and offline |
Search Facility | Limited search features | Robust email search |
Message Deletion | Can delete from server | Retains messages on server |
Storage Space Mgmt | Local device management | Centralized server storage |
Q. What is FTP?
Answer: It is a standard internet protocol provided by TCP/IP used for transmitting the files from one host to another in computer network. It can transfer files between any computers with internet connection.
Q. What file types can FTP transfer?
Answer: It can transfer ASCII file (default text files), EBCDIC file or image file(for binary files).
Q. What data structures FTP allows?
Answer: FTP allows file structure (continuos stream of bytes), record structure(file is divided into records), page structure(file is divided into pages with header and page number).
Q. What are transmisison modes of ftp?
Answer: Stream mode: data transfer in continuos stream of apps.
Block mode: Data is transferred in blocks.
Compressed mode: consecutive appearance of data unit are replaced by one occcurence to reduce number of repetitions and reduce size.
Q. What is anonymous ftp?
Answer: FTP requires user id and password on remote server. Anonymous users allows users without having an account on server. Some sites have public files which enable anonymous ftp.
About Abhishek Dhamdhere
Qna Library Is a Free Online Library of questions and answers where we want to provide all the solutions to problems that students are facing in their studies. Right now we are serving students from maharashtra state board by providing notes or exercise solutions for various academic subjects
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