CompTIA Network+ (N10-008) - Networking Protocols, Subnetting & Infrastructure Flashcards

Question 1

What is the well-known port number for HTTP (Hypertext Transfer Protocol)?

Accepted Answer

HTTP uses TCP port `80`.

Question 2

What is the well-known port number for HTTPS (Hypertext Transfer Protocol Secure)?

Accepted Answer

HTTPS uses TCP port `443`.

Question 3

What is the well-known port number for SSH (Secure Shell)?

Accepted Answer

SSH uses TCP port `22`.

Question 4

What is CIDR (Classless Inter-Domain Routing)?

Accepted Answer

CIDR is a method for allocating IP addresses and for IP routing. It replaces the old classful addressing system (A, B, C) and allows for more efficient use of IP addresses by using a variable-length subnet mask, often represented with a `/` followed by the number of bits in the network portion (e.g., `192.168.1.0/24`).

Question 5

How many usable host IP addresses are available in a `/24` subnet?

Accepted Answer

A `/24` subnet mask means 24 bits are used for the network portion. This leaves $32 - 24 = 8$ bits for the host portion. The total number of IP addresses is $2^8 = 256$. Subtracting the network address and broadcast address leaves $256 - 2 = 254$ usable host IP addresses.

Question 6

How many usable host IP addresses are available in a `/27` subnet?

Accepted Answer

A `/27` subnet mask means 27 bits are used for the network portion. This leaves $32 - 27 = 5$ bits for the host portion. The total number of IP addresses is $2^5 = 32$. Subtracting the network address and broadcast address leaves $32 - 2 = 30$ usable host IP addresses.

Question 7

For the IP address `192.168.1.10/28`, identify the network address and the broadcast address.

Accepted Answer

A `/28` subnet mask means 28 bits for the network, leaving 4 bits for hosts ($2^4 = 16$ addresses per subnet).
The subnet mask is `255.255.255.240`.
The interesting octet is the 4th. Subnet blocks are multiples of $256 - 240 = 16$.
The subnets are `...0`, `...16`, `...32`, etc.
`192.168.1.10` falls into the `192.168.1.0` to `192.168.1.15` range.
Network Address: `192.168.1.0`
Broadcast Address: `192.168.1.15`

Question 8

What is VLSM (Variable Length Subnet Masking)?

Accepted Answer

VLSM is a technique that allows network administrators to divide an IP address space into subnets of different sizes, rather than using a single subnet mask for all subnets. This optimizes IP address utilization by allocating only the necessary number of addresses for each segment.

Question 9

What is the well-known port number for DNS (Domain Name System)?

Accepted Answer

DNS primarily uses UDP port `53` for standard queries and responses. TCP port `53` is used for zone transfers between DNS servers and for DNSSEC.

Question 10

What are the well-known port numbers for FTP (File Transfer Protocol)?

Accepted Answer

FTP uses TCP port `21` for the control connection (commands) and TCP port `20` for the data connection in active mode. In passive mode, the data connection uses a random high-numbered port.

Question 11

What is the well-known port number for RDP (Remote Desktop Protocol)?

Accepted Answer

RDP uses TCP port `3389`.

Question 12

What are the well-known port numbers for SNMP (Simple Network Management Protocol)?

Accepted Answer

SNMP agents typically listen on UDP port `161` for requests from the manager. The SNMP manager sends traps/inform requests to UDP port `162` on the agent.

Question 13

What are the well-known port numbers for DHCP (Dynamic Host Configuration Protocol)?

Accepted Answer

DHCP clients send requests from UDP port `68` to UDP port `67` on the server. DHCP servers send responses from UDP port `67` to UDP port `68` on the client.

Question 14

What is OSPF (Open Shortest Path First)?

Accepted Answer

OSPF is a link-state routing protocol that uses Dijkstra's algorithm to find the shortest path for data packets. It is an interior gateway protocol (IGP) commonly used within large enterprise networks and divides networks into areas to improve scalability and reduce routing table size.

Question 15

What is BGP (Border Gateway Protocol)?

Accepted Answer

BGP is a path-vector routing protocol and the primary exterior gateway protocol (EGP) used to exchange routing information between autonomous systems (AS) on the internet. It makes routing decisions based on paths, network policies, and rulesets.

Question 16

What is EIGRP (Enhanced Interior Gateway Routing Protocol)?

Accepted Answer

EIGRP is an advanced distance-vector routing protocol developed by Cisco. It uses the Diffusing Update Algorithm (DUAL) to achieve rapid convergence. While proprietary to Cisco for many years, it was released as an open standard in 2013, though still primarily associated with Cisco environments.

Question 17

What is RIP (Routing Information Protocol) and what are its main limitations?

Accepted Answer

RIP is a distance-vector routing protocol that uses hop count as its metric. Its main limitations include a maximum hop count of 15 (making it unsuitable for large networks), slow convergence, and periodic full routing table updates which consume bandwidth.

Question 18

What is a routing table?

Accepted Answer

A routing table is a data table stored in a router or networked computer that lists the routes to particular network destinations. It contains information such as the destination network, the next-hop router, the outgoing interface, and a metric (cost) associated with the route.

Question 19

What is a VLAN (Virtual Local Area Network)?

Accepted Answer

A VLAN is a logical grouping of network devices that allows devices on different physical LAN segments to communicate as if they were on the same segment. VLANs improve network security, performance, and manageability by segmenting broadcast domains.

Question 20

What is a trunk port in the context of VLANs?

Accepted Answer

A trunk port is a switch port configured to carry traffic for multiple VLANs over a single physical link between switches or between a switch and a router. It typically uses tagging protocols like `802.1Q` to identify which VLAN each frame belongs to.

Question 21

What is `802.1Q`?

Accepted Answer

`802.1Q` is an IEEE standard for VLAN tagging on Ethernet networks. It inserts a 4-byte tag into the Ethernet frame header, which includes a 12-bit VLAN ID (allowing for 4094 VLANs) and a 3-bit Priority Code Point (PCP) for QoS.

Question 22

Describe a Star network topology.

Accepted Answer

In a Star topology, all network devices connect to a central hub, switch, or router. This is the most common topology in modern LANs.
Pros: Easy to install and manage, fault isolation (failure of one device doesn't affect others), easy to add/remove devices.
Cons: Single point of failure (central device), requires more cabling than some other topologies.

Question 23

Describe a Mesh network topology.

Accepted Answer

In a Mesh topology, every device is connected directly to every other device. This creates multiple redundant paths.
Pros: High fault tolerance and reliability, no single point of failure, robust.
Cons: Very expensive and complex to implement (especially full mesh), difficult to manage, high cabling requirements. Often used in WANs or critical backbone networks.

Question 24

Describe a Bus network topology.

Accepted Answer

In a Bus topology, all devices are connected to a single central cable, called the backbone or bus. Data travels in one direction along the bus.
Pros: Simple and inexpensive to implement for small networks.
Cons: Single point of failure (if the backbone cable breaks), difficult to troubleshoot, limited number of devices, low fault tolerance, collisions are common.

Question 25

Describe a Ring network topology.

Accepted Answer

In a Ring topology, devices are connected in a circular fashion, with each device connected to exactly two other devices, forming a single continuous pathway for signals. Data travels in one direction (unidirectional) or both (bidirectional).
Pros: Can handle high volume of traffic, no collisions, easy to install.
Cons: Failure of one device or cable can disrupt the entire network (unless dual ring), adding/removing devices can be disruptive, difficult to troubleshoot.

CompTIA Network+ (N10-008) - Networking Protocols, Subnetting & Infrastructure

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