Monday, June 25, 2012

IPV4 and IPV6

“IP” stands for the Internet Protocol which refers to the communicational protocol or a packet transfer procedure of the Internet.


Every device which connects to the Internet uses a unique IP address which is an analogue of your home address. Pieces of data are transferred via the Internet from one machine to another, and they are called “packets”. The transfer of packets will be impossible if two machines communicating through the Internet did not have the IPs.


IPv4 is an older version of an internet address procedure. Now there are no more free IPv4 addresses, all of them are already busy and soon new users will not be able to dive into the Web. That is why there appeared the necessity to have a new version of an internet address procedure.


IPv6 provided us with free IPs for a thousand years ahead.
The IPv4 supports a 32 bit address that’s why if we count we had 2^32 IP addresses. IPv6 uses 128 bit address allowing maximum 2^128 available IPs.


Comparison table of an IPv4 and IPv6 features:


IPv4


IPv6
Addresses are 32 bits (4 bytes) in length.Addresses are 128 bits (16 bytes) in length
Address (A) resource records in DNS to map host names to IPv4 addresses.Address (AAAA) resource records in DNS to map host names to IPv6 addresses.
Pointer (PTR)resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names. Pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names.
IPSec is optional and should be supported externally IPSec support is not optional
Header does not identify packet flow for QoS handling by routers Header contains Flow Label field, which Identifies packet flow for QoS handling by router.
Both routers and the sending host fragment packets.Routers do not support packet fragmentation. Sending host fragments packets
Header includes a checksum. Header does not include a checksum.
Header includes options. Optional data is supported as extension headers.
ARP uses broadcast ARP request to resolve IP to MAC/Hardware address. Multicast Neighbor Solicitation messages resolve IP addresses to MAC addresses.
Internet Group Management Protocol (IGMP) manages membership in local subnet groups. Multicast Listener Discovery (MLD) messages manage membership in local subnet groups.
Broadcast addresses are used to send traffic to all nodes on a subnet. IPv6 uses a link-local scope all-nodes multicast address.
Configured either manually or through DHCP. Does not require manual configuration or DHCP.
Must support a 576-byte packet size (possibly fragmented). Must support a 1280-byte packet size (without fragmentation).

Monday, June 18, 2012

Undo Send

Oops, hit "Send" too soon? Stop messages from being sent for a few seconds after hitting the send button.

Here’s one to help avoid all those “Oops!” moments. Google, being the awesome bunch of coders that they are, allow you to call back emails which you have just sent.
Steps to Undo the Message:

1) Go to Settings
2) Labs
3) Enable "Undo Send" functionality.
and done... :)

Next time you send an email accidentally, just call it back by clicking on Undo.