Questions in: Network & Telecom

Right Answer:
The Wi-Fi IEEE Standards are a set of specifications defined by the IEEE 802.11 family, which includes:

- 802.11a: Operates in the 5 GHz band, supports up to 54 Mbps.
- 802.11b: Operates in the 2.4 GHz band, supports up to 11 Mbps.
- 802.11g: Operates in the 2.4 GHz band, supports up to 54 Mbps.
- 802.11n: Operates in both 2.4 GHz and 5 GHz bands, supports up to 600 Mbps.
- 802.11ac: Operates in the 5 GHz band, supports up to several Gbps.
- 802.11ax (Wi-Fi 6): Operates in both 2.4 GHz and 5 GHz bands, supports higher efficiency and speeds up to 9.6 Gbps.

Right Answer:
Wi-Fi is a technology that allows electronic devices to connect to a wireless local area network (WLAN) to access the internet or communicate with each other without using physical cables.

Right Answer:
Channel bandwidth is the range of frequencies within a given band that can be used for transmitting signals, typically measured in hertz (Hz). It determines the maximum data rate that can be transmitted over a communication channel.

Right Answer:
Radio signals enable WiFi networking by transmitting data wirelessly between devices and a router using specific frequencies (typically 2.4 GHz and 5 GHz). The router converts internet data into radio signals, which are then sent through the air. Devices with WiFi capability receive these signals, decode them, and access the internet.

Right Answer:
Wi-Fi hotspots are created by connecting a device, such as a router or a smartphone, to an internet source (like a broadband connection or mobile data) and then broadcasting a wireless signal that allows other devices to connect to the internet through that device.

Right Answer:
Adaptive modulation is a technique used in telecommunications where the modulation scheme is dynamically adjusted based on the current conditions of the communication channel, such as signal quality and noise levels, to optimize data transmission rates and reliability.

Right Answer:
Wi-Fi cards are hardware components that allow devices to connect to wireless networks. They can be built into devices like laptops and smartphones or exist as separate add-on cards for desktops, enabling wireless communication using Wi-Fi standards.

Right Answer:
Wi-Fi is half duplex because it can either send or receive data at any given time, but not both simultaneously. This is due to the shared medium of the radio frequency spectrum, which requires devices to take turns communicating to avoid collisions.

Right Answer:
Wi-Fi access protocols primarily include:

1. **IEEE 802.11a** - Operates in the 5 GHz band, offering speeds up to 54 Mbps.
2. **IEEE 802.11b** - Operates in the 2.4 GHz band, offering speeds up to 11 Mbps.
3. **IEEE 802.11g** - Operates in the 2.4 GHz band, offering speeds up to 54 Mbps, backward compatible with 802.11b.
4. **IEEE 802.11n** - Operates in both 2.4 GHz and 5 GHz bands, offering speeds up to 600 Mbps through MIMO technology.
5. **IEEE 802.11ac** - Operates in the 5 GHz band, offering speeds up to several Gbps, using wider channels and advanced modulation.
6. **IEEE 802.11ax (Wi-Fi 6)** - Operates in both 2.

Right Answer:
The sluggish adoption of Wi-Fi technology can be attributed to issues such as security concerns, interference from other devices, limited range and coverage, varying standards and compatibility, high installation costs, and lack of awareness or understanding among users.

Right Answer:
The MMS (Multimedia Messaging Service) call flow typically involves the following steps:

1. **MMS Client Initiation**: The user sends an MMS message from their device.
2. **MMSC (Multimedia Messaging Service Center) Request**: The device sends a request to the MMSC to deliver the message.
3. **Authentication**: The MMSC checks the user's credentials with the Home Location Register (HLR) or Authentication Center (AuC).
4. **Message Processing**: If authenticated, the MMSC processes the message and forwards it to the recipient.
5. **Delivery Notification**: The MMSC sends a delivery report back to the sender.

An 'Authentication Error' can occur during the authentication step if the user's credentials are invalid, expired, or if there is a failure in communication with the HLR/AuC.

Right Answer:
Ping is a network utility that tests the reachability of a host on an Internet Protocol (IP) network by sending Internet Control Message Protocol (ICMP) echo request packets and waiting for a response.

Right Answer:
To force a Solaris machine not to be a router, you can disable IP forwarding by setting the following parameter:

```bash
ndd -set /dev/ip ip_forwarding 0
```

Additionally, ensure that the `/etc/default/router` file does not contain any entries.

Right Answer:
Traceroute is a network diagnostic tool that tracks the path data packets take from one computer to another, showing each hop along the way and measuring the time it takes for each hop to respond.

Right Answer:
Netstat is a command-line tool that displays network connections, routing tables, interface statistics, and other network-related information on a computer.

Right Answer:
IP addresses are unique numerical labels assigned to devices on a network, allowing them to communicate with each other. A netmask is a 32-bit number that divides an IP address into the network and host portions, determining which part of the address identifies the network and which part identifies the specific device. Subnets are smaller networks created within a larger network, allowing for better management and organization of IP addresses by grouping devices that share a common network prefix.

Right Answer:
The MAP primitives used for pinging the VLR and HLR to get Cell ID (Cid) are:

1. **SendRoutingInfo** - Used to request routing information from the HLR.
2. **ProvideSubscriberInfo** - Used to retrieve subscriber information from the VLR, which includes the Cell ID.

Right Answer:
To set a default router, use the command `ip route add default via <router_ip>` in the command line interface of your network device, replacing `<router_ip>` with the IP address of the desired default router.

Right Answer:
To add static routes, use the following command in the command line interface of your router or device:

For Cisco devices:
```
ip route [destination_network] [subnet_mask] [next_hop_ip]
```

For Linux:
```
ip route add [destination_network]/[subnet_mask] via [next_hop_ip]
```

Replace `[destination_network]`, `[subnet_mask]`, and `[next_hop_ip]` with the appropriate values for your network.

Right Answer:
Routing starts up when a router powers on and initializes its hardware, loads the operating system, and then begins to populate its routing table by discovering connected networks through protocols like RIP, OSPF, or EIGRP, or by using static routes configured by the administrator.