Computer Networking Questions and Answers | Part- 2

Computer Networking Questions and Answers | Part- 2

Level: Beginner, Intermediate and Expert

As I have told earlier in first part of the Q&A section, this is second part and will be helpful for the brainstorming and self reading purpose only.

Here we go,

1) What are SNMP Traps?

A: SNMP Traps are unsolicited messages, which are sent based on device triggers.

2) What are the two operational modes for IP SLA?

A: operation and responder

3) What is the control plane and what is it responsible for?

A: The control plane helps the data plane determine what to do with messages, and is responsible for adding MAC entries to the Layer 2 database.

4) What is best description of a SDN Controller device?

A: It can centralize decision making for many dispirit networking devices.

5) Which Command Checks the network settings ?

A: ipconfig/all

6) A server at 192.168.0.2 is trying to access clients at 192.168.4.2 and 4.200, but is having is ipconfig/all issues. What is the correct command on the server to try to troubleshoot reaching PC one?

A: [admin@ptk4]  /tool>  ping 192.168.4.2

7) Sam knows that Pinging the default gateway will force the local machine to arp for the John DHCP server's MAC address. Which command will Sam execute to correctly list the host's arp tables and the John's MAC address?

A: C:\Users\Greg>arp -a

8) Which of the following is not a valid network topology?

a. Star Bus 

b. Bus/ Linear Bus

c. Mesh Bus

d. Ring

A: Mesh Bus

9) Which coaxial cable(s) have a characteristic impedance of 50 ohms?

A: RG-8 and RG-58

10) Which characteristic(s) make UTP and STP different from each other?

A: Shielded Twisted Pair (STP) has shielding to improve noise rejection compared to Unshielded Twisted Pair (UTP). Because of the shielding, STP is more expensive than UTP.

11) Which type of fiber optic cable supports longer run lengths?

• Single Mode
• Fractal Mode
• Laser Mode
• Multi-Mode

A: Single Mode

12) Which committee governs the standards of Ethernet?

• IEEE 802.11n
• IEEE 9001
• IEEE 803
• IEEE 802.3

A: IEEE 802.3

13) Which field would not be found in an Ethernet frame?

• Source MAC Address
• Destination IP Address
• Ethertype
• Destination addres type

A: Destination IP address

14) Which of the following is a UTP wiring standard?

• TIA A568
• TIA 568B
• 10BaseT runs at 10 Mb per second
• IEEE 802.3

A: TIA 568B 

15) What is an advantages of switches over hubs?

A: Switches can use crossover or straight-through cables to connect to other switches, but hubs require crossover cables to connect to other hubs.

Switches reduce collision domains to the two ports involved in communication by isolating them from the other switch ports for the duration of the communication. All ports of a hub are on the same collision domain and can be involved in a broad spectrum of collisions. Switches can autodetect connections to other switches and internally configure the connection port to be a crossover or straight-through, as necessary.

Again we will cover more Q&A later. 

- DR

Access Control List (ACL)

Access Control List

In computer and network security, an access-control list (ACL) is a list or a table contains list of permissions associated with a system and users. An ACL specifies which users or system processes are granted access rights to objects, as well as what operations are allowed on given objects. The operations such as read, write, edit, delete, modify, alter, allow, deny, block etc.

In case of Linux systems, it offers three types of permissions to User, Group and other such as Read, Write and Execute. ACLs allow us to apply a more specific set of permissions to a file or directory without (necessarily) changing the base ownership and permissions.

Here we are not covering Linux systems in this section. We will use windows system for now.  Read permission allows the user to view the contents of the file. Read and execute permission goes beyond the read permission and it also allows the users to run executable programs. Write permission allows the users to create files and add data to them. Modify goes beyond write to allow the user to delete files. It also adds read and execute permissions not already present in the write permission group.

This is how the ACL is prepared. The ACL is very critical in view of security at any Data Centers, any WAN networks or at any Cloud Service Provider.

Why we use ACL if we have Firewall for traffic control?

Through ACL we can get;

• Traffic Control
• Restricted network traffic 
• Better network performance
• Another layer of security over firewall
• We can specify the access right for different zones in a network.
• Provide bandwidth control
• Provide NAT control
• Reduce the chance of DoS attack

There are various types of ACL being used such as File system ACL, Active Directory ACL, Networking ACL, Canned ACL (Amazon S3)

In case of networking and networking devices it can be considered as a tool define traffic and control the traffic. It acts as a set of rules configured for controlling the network traffic and reducing network attack. It is used to filter traffic based on the set of rules defined for the incoming or outgoing traffic of the network.

While configuring the ACL remember,

Only one ACL per interface, per protocol, per direction is allowed.

Example

Applying an Access List to an Interface, steps are as;

• enable

• configure terminal

• interface type number

• ip access-group {access-list-number | access-list-name} {in | out}

• end

Creating an IP named ACL

Rtr# configure terminal 

Rtr(config)# ip access-list extended acl1

Rtr(config-ext-nacl)# remark protect server by denying sales access to the acl1 network

Rtr(config-ext-nacl)# deny ip X.X.X.X  0.0.255.255 host X.X.X.X log

Rtr(config-ext-nacl)# remark allow TCP from any source to any destination

Rtr(config-ext-nacl)# permit tcp any any

Cloud ACL

Now let us know about the cloud ACL. For example, if we take AMAZON S3 Console Access Control List, the permissions are READ, WRITE, READ_ACP, WRITE_ACP, FULL CONTROL. Just take READ and WRITE to know what it actually allows;

READ: It Allows grantee to list the objects in the bucket and for object, it allows grantee to read the object data and its metadata. (A grantee can be an AWS account or one of the predefined Amazon S3 groups)

WRITE: Allows grantee to create new objects in the bucket. For the bucket and object owners of existing objects, also allows deletions and overwrites of those objects.

 -DR

Telecom | STM-1/4/16 SDH Multiplexer- Part 2

STM-1/4/16 SDH Multiplexer

In my older post I have covered the basic STM and STM-1. STM1 is a synchronous digital hierarchy (SDH) is standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers or light emitting diodes (LEDs).

The STM-1 / STM-4 can be managed through an integrated NMS to manage all the equipment, providing customers through end-to-end provisioning from a single platform for multiple service types such as E1/DS1s, E3/DS3s, E4/STM-1e and STM-1o. In some equipment, vendors provide 10/100Mbps Ethernet services and single 10/100Base-T Ethernet port. Some STM-1 OEMs offers both electrical STM-1 (1+1) and optical STM-1 (1+1) interfaces. It can be customized for the traffic demands, in the access network, typical of residential or business needs at organizations. The System comes with latest optical networking software with the intelligence of SONET/SDH to deliver a flexible, cost-effective network solution.

Many OEMS have their STM multiplexer product in market such as Gigabit, GL Communication, VCL100MC-1 STM-1, Data Connect Enterprise, Patton Electronics, E-Link,  AN-STM-1-ETH (AD-Net) etc.

(Source: AN-STM-1-ETH (AD-Net))

(Source: GL Telecommunication Inc.)

If we talk about the device or multiplexer itself, let’s see an example with basic features of one STM Device such as VCL 100MC of VALIANT COMMUNICATIONS. For more information and technical specification, you can refer to the data sheet at respective website of Valiant Communication provided below. 

(Source: https://www.valiantcom.com/stm/stm-1-4/data_sheet/vcl-stm-4.pdf)

Valiant VCL100 is an ultra-compact, carrier class and cost-effective bandwidth provisioning STM1/4/16 SDH Multiplexer equipment designed to manage and deliver services from the optical core to the access.

The STM-1/4/16 SDH Multiplexer equipment supports end-to-end provisioning and management of services across all segments of the optical network. It combines innovative optical networking software with the resilience of SDH to deliver a flexible solution to today's service providers.

The VCL100 can be configured as a Terminal Multiplexer (TMUX), Add-Drop Multiplexer (ADM), Regenerator, In-Line Amplifier or as a stand-alone Cross-Connect. A variety of service interfaces such as E1/DS1, E3/DS3, STM-1e/o and 10/100/1000 Mbps Ethernet tributary interfaces and trunk interfaces at STM-1/4/16 rates are supported. The product features non-blocking cross connect at VC-3, VC-4 and VC-12 granularity and supports drop and continue functionality.

Some glance of Features

• They are Compact in size.
• Integrated multi-service Delivery 
• Redundant cards with hot insertion capability 
• Multi-level protection schemes MSP, or SNCP
• Advanced networking software with support for open standards such as GMPLS and OSPF.

And if we considering the operating environment, all the devices work under -5 degree to 50 degree Celsius temperature and 10% to 90% of humidity range. 

So for more information or technical datasheet please refer to OEM websites. 

Note: This is not paid promotion for any vendor/OEM. This post in not violating copy right as the source reference ID provided here. 

-DR