Networking Tips Tricks

Quadrature Phase-shift Keying Sometimes known as quaternary or quadriphase PSK or 4-PSK, QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol-twice the rate of BPSK. This is used either to double the data rate compared to a BPSK system while maintaining the bandwidth of the signal or to maintain the data-rate of BPSK but halve the bandwidth needed. Although QPSK can be viewed as a quaternary modulation, it is easier to see it as two independently modulated quadrature carriers. With this interpretation, the even (or odd) bits are used to modulate the in-phase component of the carrier, while the odd (or even) bits are used to modulate the quadrature -phase component of the carrier. BPSK is used on both carriers and they can be independently demodulated.

BPSK is the simplest form of PSK. It uses two phases which are separated by 180° and so can also be termed 2-PSK. It does not particularly matter exactly where the constellation points are positioned It is, only able to modulate at 1bit/symbol and so is unsuitable for high data-rate applications.

Modulation is the process by which a carrier wave is able to carry the message or digital signal (series of ones and zeroes). There are three basic methods to this:- Amplitude, Frequency Phase shift keying. Higher orders of modulation allow us to encode more bits per symbol or period (time).

Technical details Schema of a typical DHCP session DHCP uses the same two IANA assigned ports as BOOTP: 67/udp for the server side, and 68/udp for the client side. DHCP operations fall into four basic phases. These phases are IP lease request, IP lease offer, IP lease selection, and IP lease acknowledgement. After the client obtained an IP address, the client may start an address resolution query to prevent IP conflicts caused by address poll overlapping of DHCP servers. DHCP discovery The client broadcasts on the local physical subnet to find available servers. Network administrators can configure a local router to forward DHCP packets to a DHCP server on a different subnet. This client-implementation creates a UDP packet with the broadcast destination of 255.255.255.255 or subnet broadcast address. A client can also request its last-known IP address (in the example below, 192.168.1.100). If the client is still in a network where this IP is valid, the server might grant the request. O...

Requirement Cisco Command Enable debug for RIP debug ip rip Enable summary IGRP debug information debug ip igrp events Enable detailed IGRP debug information debug ip igrp transactions Debug IPX RIP debug ipx routing activity Debug IPX SAP debug IPX SAP Enable debug for CHAP or PAP debug ppp authentication Switch all debugging off no debug all undebug all

Requirement Cisco Command Save the current configuration from DRAM to NVRAM copy running-config startup-config Merge NVRAM configuration to DRAM copy startup-config running-config Copy DRAM configuration to a TFTP server copy runing-config tftp Merge TFTP configuration with current router configuration held in DRAM copy tftp runing-config Backup the IOS onto a TFTP server copy flash tftp Upgrade the router IOS from a TFTP server copy tftp flash

Requirement Cisco Command Enter privileged mode Enable Return to user mode from privileged disable Exit Router Logout or exit or quit Recall last command up arrow or Recall next command down arrow or Suspend or abort and 6 then x Complete Command TAB

Requirement Cisco Command View version information show version View current configuration (DRAM) show running-config View startup configuration (NVRAM) show startup-config Show IOS file and flash space show flash Shows all logs that the router has in its memory show log View the interface status of interface e0 show interface e0 Overview all interfaces on the router show ip interfaces brief View type of serial cable on s0 show controllers 0 (note the space between the 's' and the '0') Display a summary of connected cdp devices show cdp neighbor Display detailed information on all devices show cdp entry Display current routing protocols show ip protocols Display IP routing table show ip route Display access lists, this includes the number of displayed matches show access-lists Check the router can see the ISDN switch show isdn status Check a Frame Relay PVC connections show frame-relay pvc show lmi traffic stats show frame-relay lmi Display the frame inverse ARP table s...

Requirement *Cisco Command* Set a console password to cisco Router(config)#*line con 0* Router(config-line)#*login* Router(config-line)#*password cisco* Set a telnet password Router(config)#*line vty 0 4* Router(config-line)#*login* Router(config-line)#*password cisco* Stop console timing out Router(config)#*line con 0* Router(config-line)#*exec-timeout 0 0* Set the enable password to cisco Router(config)#*enable password cisco* Set the enable secret password to peter. This password overrides the enable password and is encypted within the config file Router(config)#*enable secret peter* Enable an interface Router(config-if)#*no shutdown* To disable an interface Router(config-if)#*shutdown* Set the clock rate for a router with a DCE cable to 64K Router(config-if)*clock rate 64000* Set a logical bandwidth assignment of 64K to the serial interface Router(config-if)*bandwidth 64* *Note that the zeroes are not missing* To add an IP address to a interface Router(config-if)#*ip addr 10.1.1.1 ...

*Understanding Patches* When vendors become aware of vulnerabilities in their products, they often issue patches to fix the problem. Make sure to apply relevant patches to your computer as soon as possible so that your system is protected. *What are patches?* Similar to the way fabric patches are used to repair holes in clothing, software patches repair holes in software programs. Patches are updates that fix a particular problem or vulnerability within a program. Sometimes, instead of just releasing a patch, vendors will release an upgraded version of their software, although they may refer to the upgrade as a patch. *How do you find out what patches you need to install?* When patches are available, vendors usually put them on their websites for users to download. It is important to install a patch as soon as possible to protect your computer from attackers who would take advantage of the vulnerability. Attackers may target vulnerabilities for months or even years after patches are av...

1. Name another way of joining a PC to domain? 2. A manager cannot print to a network printer but all other users can, what do you do? 3. What’s the printer registry file name? 4. Name 5 reasons why a user might not be able to logon to the network? 5. Explain how DHCP works? 6. A user has a laptop that runs fast on the network (at work) but slow at home? Explain what could be the problem. 7. Explain how to share outlook calendars and the type of permissions you need to assign? 8. A user can log on to the network but has no internet connection? Explain what could be the problem. 9. A user’s application on their desktop is not working; explain what you would do to resolve this problem? 10. What is the difference between a UNC and drive mapping? 11. How do you import external data into an Excel spreadsheet? 12. What is a mail merge and how does it work? 13. Explain what TCP/IP is and how it works? 14. A user operating his laptop from home finds it very slow, but when using the laptop a...

How to disable USB Pendrive /USB Storage Device using Server Group Policy? Ans: follow the 4 steps below. 1.) Take the following text, copy it, and paste it into a text document. Then, save it as USBSTOR.ADM. CLASS MACHINE CATEGORY "Custom Policies" KEYNAME "SYSTEM\CurrentControlSet\Services\UsbStor" POLICY "USB Mass Storage Installation" EXPLAIN "When this policy is enabled, USB mass storage device permissions can be changed by using the drop down box. Selecting 'Grant Permission' will allow USB mass storage devices to be installed. Selecting 'Deny Permission' will prohibit the installation of USB mass storage devices. IF REMOVING THIS POLICY: Reset to original setting and let policy propegate before deleting policy." PART "Change Settings:" DROPDOWNLIST REQUIRED VALUENAME "Start" ITEMLIST NAME "Grant Permission" VALUE NUMERIC 3 DEFAULT NAME "Deny Per...

The Challenge: The unimpeded growth of data centers over the last decade along with the popularity of distributed applications has resulted in a proliferation of servers, storage systems, and operating systems. Most of these applications are on isolated, single-function physical servers that are over-sized and under-utilized. The result: Single function servers and application silos are wasting capacity. Administration costs are exorbitant due to the increased complexity and lack of manageability of the data center environment. Managing, patching, and securing servers is cumbersome, error-prone and time consuming. Our Solution: Virtual Iron streamlines and automates server consolidation and reduces complexity throughout the data center. The software creates an optimized "virtual" data center that provides dynamic infrastructure built on industry standards and is flexible to changing business needs. The Virtual Iron platform allows a physical server of any size (from a single ...

Terminal Services Gateway (TS Gateway) is a role service in the Terminal Services server role of Windows Server® 2008 that allows authorized remote users to connect to resources on an internal corporate or private network, from any Internet-connected device. The network resources can be terminal servers, terminal servers running RemoteApp programs, or computers with Remote Desktop enabled. TS Gateway uses Remote Desktop Protocol (RDP) over HTTPS to establish a secure, encrypted connection between remote users on the Internet and the internal network resources on which their productivity applications run. What does TS Gateway do? TS Gateway provides many benefits, including: •TS Gateway enables remote users to connect to internal network resources over the Internet, by using an encrypted connection, without needing to configure virtual private network (VPN) connections. •TS Gateway provides a comprehensive security configuration model that enables you to control access to specific int...