Network Security 1 - Application Layer Flashcards
What are the examples of network Applications ?
Email Service ,
web browser,
SSS login,
Telnet, file transfer,
multi user Network games, ,
real time video conferencing ,
social networking
What network applications mean and where it runs?
Network application means user applications running onEnd Systems, and Software running on routers and switches are different.
What are the modern paradigm or architecture of network applications ?
We have two types of network architecture,
1. Client-Server network architecture
2. Peer-to-Peer network architecture
3. Hybrid network architecture
What are the components of client server model ?
- A server
- Clients
In a client-server architecture can client communicate to each other directly ?
No they cannot communicate to each other directly ?
What are hybrid network applications ?
Network applications using both architectures , peer to peer and client server
These types of network applications are called hybrid network applications.
What is a web page ?
Web page is a document which contains, base HTML file & several referenced objects , like imagefiles, audio files
What are the components of URL ?
Each URL has two component ,
1. The hostname of the server
2. Path of the object itself
What is HTTP ?
Http hypertext transfer protocol , it works on client server architecture. It is an web application layer protocol,
In HTTP protocol web browser request to server using HTTP protocol and and web server responses to request
What are the objects in web page ?
Images, audio files, text, videos , or any other reference object in HTML file document.
All these are known as web page objects.
What are the types of http connections ?
Http connections are of two types.
1. Persistent http connections
2. Non persistent http connections
In persistent TCP connection multiple object can be sent over single TCP connection between client and server , and connection is closed.
But in non-persistant http connection only single object is sent over single http connection , and connection is closed , Downloading multiple objects require multiple http connections
What are http response codes ?
when internet is not working, web browser shows Error Codes with description in first line.
Some of them are are:
200 ok
301 moved permanently
400 bad request
404 Not Found
505 http version not supported
What is a command in Linux to get http response code ?
curl -o - -I url
What are web cache ?
Web Cache Is used to satisfy client request without involving original server.
What is an email system ?
Electronic mail (e-mail), a system that allows users to send and receive messages through a computer network.
What is SMTP ?
SMTP stand for simple mail transfer protocol,
This protocol is used between email servers to send messages
What is POP3 and IMAP protocol ?
POP3 stands for Post Office protocol , and IMAP stand for internet message access protocol . These protocol are used by email clients to fetch messages from an email server
What is POP3 ?
It stands for, Post office protocol version 3
On which port POP3 protocol will work ?
POP3 work on two ports,
1. Port 110 for non-encrypted communication
2. Port 995 for encrypted communication
What are the limitations of POP3 protocol ?
POP3 Only create folder on email client or in desktop only , it cannot create folder on server itself, for this scenario you have to use IMAP protocol.
POP3 protocol cannot read header or metadata of email.
What is the difference between POP3 and IMAP protocol ?
POP3 responsible for managing the emails in the local side,
Whereas IMAPprotocol is responsible for managing emails on remote side or server side
What is the difference between web based email & Email Client ?
Web based email using HTTP protocol to communicate with email server, email client uses POP3 or IMAP protocol to communicate with email server
What is DNS ?
Domain Name System ,
It is a hierarchical system of distributed name server databases that contain information on domains and host within those domains.
DNS is used to convert hostname to IP addresses
What are the levels of DNS server ?
There are multiple levels of DNS servers, top level is called root DNS server,then TLD Server , then Aurhorative DNS Server . Root DNS Server has address of TLD Servers,TLD Servers has address of Authoritative DNS Server
List some DNS Services >
Some of them are:
1. Host aliasing - same host is redirected to multiple IP addresses
2. Mail server aliasing
3. Load distribution or DNS Caching
4. Translate hostname to IP addresses
How DNS works ?
Primary work of DNS is to convert hostname to IP address,
When a cl;ient to wants to communicate to host , it passes the hostname to DNS application, then DNS application searches the local system for hostname entry , if entry not found in the local system , DNS application sends a query containing the hostname to a DNS server, DNS client receives the reply , which include the IP address for the hostname.
What is iterative DNS query ?
XYZ
Root DNS Server - Contains Address of TLD Servers based on Top Level Domain
TLD DNS Server - Contains Address of name server
Authorative DNS Server - Keep records of Domain
What is recursive DNS query ?
Root DNS Server is responsible to provide IP to LocalDNS Server
What is CDN ?
Content Distribution network - also known as content delivery network, is a large geographical distributed network of specialised servers that accelerate the delivery of web content and rich media to internet connected devices
What is an LDNS ?
Local DNS server
