What is Unicast, Broadcast and Multicast

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• What is Unicast, Broadcast and Multicast
• AVG antivirus users in reboot chaos after bad update
• Companies slow to adopt NAC technology
• Top Security Predictions for 2011
• Wikleaks struggles back online at new address
• Bruce Schneier: 'Cyberwar hotlines' needed
• Protect Your Android Phone With Security Apps
• AT&T, BT offer Inter-Provider Cisco TelePresence
• Hackers issue bogus Amber Alert
• Google quashes 13 Chrome bugs, adds PDF viewer
• AVG Free Update Bricks 64-Bit Windows 7 PCs
• WikiLeaks.org downed by domain hosting service
• WikiLeaks incidents stoke IT security angst
• The holy grail of PC security?

What is Unicast, Broadcast and Multicast Posted: 03 Dec 2010 12:12 PM PST For a CCNA certification exam you must be prepared to answer questions about three important networking concepts, Unicast, Broadcast and Multicast. Even if these terms can be pretty confusing at the beginning, they are actually not that complicated. Learn how to keep them straight, along with other vital CCNA exam information. At the beginning of your CCNA preparation studies, you will encounter some networking terminology that sounds alike between them. You will hear all the time the terms unicast, broadcast and multicast so we will try to explain their differences here in both Layer 2 and Layer3 levels. Unicast: Unicast is a packet/frame (or flow of packets/frames) that has a single destination. This is the most common kind of traffic that we see in TCP/IP networks. When for example you access a web server, this is a unicast traffic. Broadcast: A broadcast is a packet/frame (or flows of packets/frames) that are destined for ALL devices on the network/segment. Every bit of the destination address in the packet will be binary "1". A broadcast IP address (in Layer 3) is 255.255.255.255. A broadcast Layer2 address is ff-ff-ff-ff-ff-ff. Every host on a segment will receive such a broadcast. (Keep in mind that switches will forward a broadcast, but routers do not). Broadcast traffic is used to announce something to all hosts. For example, ARP (address resolution protocol) uses a broadcast address to propagate. Multicast: Multicast is the middle ground between unicast and broadcast. Multicast traffic is destined to a "group" of hosts, called "multicast group". Hosts register into a multicast group in order to receive the traffic which is destined to that group. Multicast is used in Video over IP communication for example. For your CCNA studies you need only keep certain multicast groups in mind. Class D addresses are reserved for multicasting this range is 224.0.0.0 – 239.255.255.255. The addresses 224.0.0.0 – 224.255.255.255 are reserved for use by network protocols on a local network segment, and like broadcasts, routers will not forward these multicast packets. Some other examples of multicast traffic include OSPF hello packets (which are sent to multicast address 224.0.0.5), EIGRP updates sent to 224.0.0.10, and RIP version 2 uses 224.0.0.9 to send routing updates.

AVG antivirus users in reboot chaos after bad update Posted: 03 Dec 2010 08:00 AM PST Antivirus company AVG has had to issue roll-back instructions to users of the free edition of its AVG 2011 program after 64-bit versions of Windows fail to reboot correctly after a mandatory update.

Companies slow to adopt NAC technology Posted: 03 Dec 2010 08:00 AM PST Forrester has made a set of predictions for NAC technology in 2011

Top Security Predictions for 2011 Posted: 03 Dec 2010 08:00 AM PST Aside from the festivities of the holidays, one thing that always makes December special is the combination of reflecting on the year gone by, and looking ahead to what the next year might hold. It is filled with top 10 lists and predictions on every imaginable topic.

Wikleaks struggles back online at new address Posted: 03 Dec 2010 08:00 AM PST Wikileaks is struggling to return at a new web address, wikileaks.ch, after hoster EveryDNS.net threw in the towel in the face of a sustained distributed denial of service (DDoS)attack.

Bruce Schneier: 'Cyberwar hotlines' needed Posted: 03 Dec 2010 08:00 AM PST Security expert Bruce Schneier has called for governments to establish 'hotlines' between their cyber commands, much like the those betwen nuclear commands, to help them battle against cyber attacks.

Protect Your Android Phone With Security Apps Posted: 03 Dec 2010 08:00 AM PST You back up data on your computer in case it crashes, and you might install LoJack on your car to help recover it in case someone steals it--so why shouldn't you protect your Android phone? Most people carry a lot of sensitive data on their phones. If someone steals your handset or if you happen to lose it, all that personal information is suddenly not so personal anymore. Your phone is an investment, so you should safeguard your contacts, photos, texts, videos, and music.

AT&T, BT offer Inter-Provider Cisco TelePresence Posted: 03 Dec 2010 08:00 AM PST AT&T and BT have announced an agreement to offer Inter-Provider Cisco TelePresence, providing exchange-to-exchange telepresence meeting capability. The new interoperability between AT&T and BT telepresence exchanges will allow their respective business customers to schedule and seamlessly connect telepresence endpoints. The commercial availability follows a successful trial conducted last summer.

Hackers issue bogus Amber Alert Posted: 03 Dec 2010 08:00 AM PST Iowa's Amber Alert website was hacked and used to send out a bogus alert over the weekend.

Google quashes 13 Chrome bugs, adds PDF viewer Posted: 03 Dec 2010 08:00 AM PST Google on Thursday patched 13 vulnerabilities in Chrome as it shifted the most stable edition of the browser to version 8.

AVG Free Update Bricks 64-Bit Windows 7 PCs Posted: 03 Dec 2010 08:00 AM PST If you haven't already downloaded the latest mandatory AVG 2011 Free software update, it may be best not to if you want your computer to turn on again. The December 1 update is causing 64-bit PCs running Windows 7 to totally breakdown.

WikiLeaks.org downed by domain hosting service Posted: 03 Dec 2010 08:00 AM PST WikiLeaks' main website could not be accessed on Friday through its WikiLeaks.org domain name after a subsidiary of Dynamic Network Services terminated its domain name service.

WikiLeaks incidents stoke IT security angst Posted: 03 Dec 2010 08:00 AM PST IT pros warn that enterprises without adequate security processes are vulnerable to insider leaks of sensitive information.

The holy grail of PC security? Posted: 02 Dec 2010 08:00 AM PST Monitoring user inactivity, and locking down a computer when the user forgets to, is the Holy Grail of PC security.

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