Chapter 10: Data Communication and Internet Services (Set-8)
In a noisy wireless link, which approach most directly improves reliability without changing bandwidth
A Longer URL paths
B Lower DNS TTL
C Static IP only
D Error detection codes
Error detection like CRC helps receivers detect corrupted frames caused by noise. When errors are found, retransmission or correction methods can be used, improving reliability even if the channel remains noisy.
When data is converted into a signal suitable for a particular medium, the process is called
A Encoding process
B Name resolution
C Port forwarding
D Cache validation
Encoding converts data into signals that can travel over the medium, such as electrical pulses or radio changes. Proper encoding helps receivers interpret bits correctly and reduces errors under noise.
In full-duplex Ethernet, collisions are avoided mainly because
A DNS caching enabled
B DHCP lease fixed
C Separate transmit paths
D HTTP uses GET
Full-duplex links use separate transmit and receive paths, so devices don’t compete on the same shared medium. This removes collision behavior typical of shared half-duplex Ethernet segments.
Which OSI layer is most responsible for converting network addresses to local physical delivery on a LAN
A Application layer
B Session layer
C Presentation layer
D Data Link layer
The Data Link layer handles local delivery using frames and MAC addressing. It ensures data moves correctly within the same network segment and includes error detection for link reliability.
A router makes forwarding decisions mainly based on
A Destination MAC only
B Destination IP address
C Cookie value
D DNS record type
Routers operate at the Network layer and route packets using destination IP addresses. MAC addresses are used for local next-hop delivery, but routing decisions are based on IP networks.
In TCP/IP, encapsulation means data is wrapped with
A Only MAC addresses
B Only DNS responses
C Layer-specific headers
D Only DHCP options
As data moves down the stack, each layer adds its own header, like TCP/UDP and IP. These headers carry addressing and control information needed for routing and correct delivery.
A key reason TCP is slower than UDP in some cases is because TCP
A Uses connection setup
B Uses no headers
C Avoids acknowledgments
D Sends no segments
TCP creates a connection using a handshake and adds reliability features like acknowledgments and retransmissions. This overhead can increase latency compared to UDP for some simple or real-time uses.
DNS primarily converts
A IP to MAC
B MAC to port
C Port to URL
D Domain to IP
DNS resolves human-readable domain names into IP addresses so clients can connect to the correct server. This allows users to access services using names rather than numeric addresses.
A DNS “cache” is used mainly to
A Encrypt all queries
B Change domain ownership
C Speed repeated lookups
D Reduce bandwidth limits
Caching stores DNS answers for a time based on TTL. This reduces repeated queries to DNS servers and makes access faster for commonly visited sites.
The “DHCP offer” message is sent by the
A DNS resolver
B DHCP server
C Web browser
D FTP client
After receiving a client discovery message, the DHCP server replies with an offer containing an available IP address and configuration options. The client can accept it to obtain settings.
DHCP helps prevent manual configuration mistakes by
A Auto assigning settings
B Forcing static IP
C Disabling DNS cache
D Encrypting SMTP
DHCP automatically provides IP, subnet mask, gateway, and DNS settings. This reduces human error, speeds setup, and avoids conflicts that happen when users manually choose duplicate addresses.
The main job of a subnet mask is to
A Encrypt web traffic
B Assign MAC addresses
C Block DNS queries
D Define network boundary
The subnet mask tells which part of an IP address is the network and which part is the host. Devices use it to decide whether traffic is local or must go to the gateway.
The default gateway is required when accessing
A Local LAN devices
B Only DNS server
C Outside subnet networks
D Same IP host
If the destination is not in the local subnet, packets must be forwarded by a router. The default gateway provides that forwarding path to other networks, including the internet.
HTTPS provides security mainly by using
A TLS encryption
B UDP routing
C DHCP lease time
D DNS recursion
HTTPS uses TLS to encrypt traffic and protect it from eavesdropping and tampering. Certificates help verify the server’s identity, making browsing safer for sensitive activities.
Which item most directly confirms a website identity during HTTPS setup
A Subnet mask
B MAC address
C FTP username
D Digital certificate
Certificates bind a domain to a public key and are signed by trusted authorities. Browsers validate them to confirm the server identity and then establish encrypted communication.
In a URL, the “path” part mainly identifies
A DNS server name
B Router interface
C Resource location
D IP lease time
The path tells the server which specific page, file, or resource is requested after the domain. It helps locate content within the website’s directory or application routing structure.
In HTTP, a “status code” mainly tells
A Packet size limit
B Request result meaning
C DNS cache time
D DHCP pool size
HTTP status codes indicate how the server handled the request, such as success, redirect, client error, or server error. Browsers use codes to decide the next action.
HTTP 301 is used for
A Temporary redirect
B Server failure
C Permanent redirect
D Unauthorized access
A 301 response tells clients the resource has permanently moved to a new URL. Browsers and search engines may update stored links based on this response.
Cookies are mainly used to store
A DNS zone data
B Routing table info
C Modulation settings
D Small client state
Cookies store small values in the browser, like session identifiers and preferences. They help websites maintain user state across multiple HTTP requests, which are otherwise stateless.
A session ID is commonly stored in a
A Browser cookie
B DNS record
C DHCP lease
D Router table
Most websites store session data on the server and keep only a session ID in the browser cookie. This links the browser to server-side state like login and activity.
FTP is a protocol mainly used to
A Resolve names
B Encrypt web traffic
C Transfer files
D Assign dynamic IP
FTP moves files between a client and server and supports upload and download. Classic FTP is not encrypted, so secure alternatives are used when confidentiality is required.
The standard FTP control port is
A Port 25
B Port 21
C Port 80
D Port 443
Port 21 is used for FTP control commands like login and directory operations. Actual data transfer uses additional connections, which is why FTP may need special firewall rules.
SFTP is best described as
A Web page protocol
B Name mapping service
C Dynamic IP method
D Secure file transfer
SFTP transfers files over an encrypted connection, commonly using SSH. It protects credentials and data, unlike plain FTP which can expose them on untrusted networks.
Port 25 is commonly associated with
A HTTP browsing
B DNS queries
C SMTP mail transfer
D FTP control
SMTP uses port 25 mainly for server-to-server mail transfer. Email clients often submit outgoing mail using port 587, but the classic SMTP relay port remains 25.
POP3 is mainly used to
A Retrieve email
B Send email
C Host websites
D Assign addresses
POP3 downloads email from the server to a client, often storing messages locally. It is simple but less suited for multiple devices compared to IMAP synchronization.
IMAP is mainly used to
A Transfer files
B Route packets
C Encrypt websites
D Sync email mailbox
IMAP keeps mail on the server and synchronizes it across devices. It supports folders and read/unread states, making it ideal for users who check email on multiple devices.
The ping command uses
A SMTP commands
B HTTP headers
C ICMP messages
D FTP control codes
Ping sends ICMP echo requests and waits for replies. It checks reachability and measures round-trip delay, helping diagnose basic connectivity issues between devices on a network.
Traceroute works mainly by analyzing
A TTL expirations
B Cookie lifetimes
C DHCP renewals
D DNS records
Traceroute sends packets with increasing TTL values. Routers reduce TTL; when it reaches zero, routers send ICMP responses, allowing traceroute to list hops along the path.
A proxy server can improve performance using
A Increasing noise level
B Changing MAC address
C Reducing bandwidth
D Caching web content
Proxy caching stores copies of frequently accessed resources. Reusing cached resources reduces repeated internet downloads, speeds up browsing, and saves bandwidth for organizations.
A VPN is mainly used to provide
A Faster DNS lookup
B Encrypted private tunnel
C Longer DHCP lease
D Higher attenuation
A VPN encrypts traffic between your device and a VPN server, improving privacy and security. It can also allow secure access to private networks from remote locations.
NAT is widely used because it
A Removes encryption need
B Replaces routing tables
C Saves public IPv4
D Stops packet switching
NAT allows many private devices to share one public IPv4 address. It translates internal addresses to the public address, conserving limited IPv4 space and enabling home networks to connect easily.
A MAC address is used mainly within
A Global internet routing
B DNS root network
C Web application layer
D Local LAN segment
MAC addresses are used for local frame delivery on a LAN. Routers use IP addresses for end-to-end routing, while MAC addresses typically change at each hop.
An ISP provides users with
A Internet connectivity
B DNS record signing
C Packet segmentation
D TCP sequencing
An ISP connects homes and offices to the internet through fiber, cable, or mobile networks. Many ISPs also provide DNS servers, modems, and basic customer support services.
Web hosting means
A Assigning static MAC
B Mapping IP to MAC
C Storing site online
D Modulating signals
Web hosting stores website files on an internet-connected server. Hosting providers supply storage, bandwidth, uptime, and web server software so the site can be accessed publicly.
VoIP sends voice as
A DNS zone entries
B DHCP lease values
C TCP window sizes
D IP data packets
VoIP converts voice into digital packets and sends them across IP networks. Good quality requires stable connections with low delay and minimal jitter or packet loss.
The purpose of “protocol suite” is to provide
A Only one protocol
B Multiple working protocols
C Only cables rules
D Only MAC mapping
A protocol suite is a set of related protocols designed to work together, like TCP/IP. It includes protocols for routing, transport, and services such as web, email, and DNS.
Data link frames usually include
A Only domain name
B Only IP address
C Source and destination MAC
D Only URL path
Frames at the Data Link layer use MAC addresses for local delivery. They encapsulate higher-layer data and often include error-checking fields to detect corruption on the link.
A packet’s IP header typically includes
A Source and destination IP
B Source MAC only
C DNS TTL value
D HTTP status code
The IP header includes source and destination IP addresses so routers can forward packets across networks. It also includes other fields like TTL and protocol type for proper routing.
A common reason for low throughput is
A Longer domain name
B Larger subnet mask
C Congestion and retransmits
D More cookies saved
Congestion causes delays and packet drops, leading to retransmissions in reliable protocols like TCP. Overhead and repeated sending reduce actual throughput compared to the link’s theoretical bandwidth.
A browser padlock icon usually indicates
A DNS is disabled
B DHCP is stopped
C FTP is secure
D HTTPS is active
The padlock generally means the connection uses HTTPS with a valid certificate. Traffic is encrypted and integrity-protected, helping reduce interception and tampering risks during browsing.
HTTP is called “stateless” because it
A Encrypts every request
B Remembers nothing by default
C Uses only UDP
D Requires DHCP always
Each HTTP request is independent. The protocol does not store user state automatically, so websites use cookies and sessions to maintain logins, carts, and preferences across requests.
SMTP, POP3, and IMAP are all related to
A Web browsing
B File transfers
C Email services
D IP leasing
SMTP sends email, while POP3 and IMAP retrieve and manage mailboxes. Together they support common email functions: sending, receiving, and synchronizing messages across clients and servers.
Which pair is correctly matched with web ports
A HTTP 25, HTTPS 53
B HTTP 21, HTTPS 110
C HTTP 143, HTTPS 995
D HTTP 80, HTTPS 443
HTTP commonly uses port 80 for unencrypted web traffic, while HTTPS uses port 443 for encrypted traffic via TLS. These are standard ports recognized by browsers and servers globally.
FTP can be risky on public networks mainly because
A Plain text credentials
B Uses too much DNS
C Needs subnet mask
D Uses MAC routing
Basic FTP may send usernames and passwords without encryption. Attackers can capture credentials on open networks, so secure alternatives like SFTP or FTPS are recommended for sensitive transfers.
A common benefit of DNS is that it
A Encrypts all traffic
B Prevents NAT use
C Avoids remembering IPs
D Removes all noise
DNS lets users access services using easy domain names instead of numeric IP addresses. It also supports changes behind the scenes by updating records without changing user-facing names.
DHCP is helpful in large networks because it
A Increases attenuation
B Reduces manual setup
C Removes routing needs
D Blocks traceroute
DHCP automates network configuration for many devices, reducing effort and errors. It prevents common problems like duplicate IP addresses and speeds up device onboarding on LANs.
HTTP redirects are useful when
A DNS is broken
B Subnet is wrong
C MAC is missing
D URL has changed
Redirects send users to a new location when content moves. They maintain usability, help search engines update links, and support changes like switching from HTTP to HTTPS.
In TCP/IP, the “application layer” includes protocols like
A IP and ARP
B Ethernet and Wi-Fi
C HTTP and DNS
D CRC and FEC
In TCP/IP, application protocols include HTTP, DNS, SMTP, and FTP. They support user services like browsing, name resolution, and email, operating above transport protocols like TCP/UDP.
A “resolver” in DNS is the component that
A Finds IP for name
B Assigns IP lease
C Encrypts web pages
D Transfers files
The resolver queries DNS servers to translate a domain name into an IP address. It may cache results for speed, and it can be part of the OS, router, or ISP service.
A common reason to use caching in networks is
A Increase packet loss
B Increase signal noise
C Reduce repeated requests
D Change MAC address
Caching stores recent results or content so the same data need not be fetched repeatedly. It saves bandwidth, reduces server load, and improves response time for users accessing common resources.