1. Routing tables and how the router will perform a route lookup:
a. Routing Table Format- A routing table is used by TCP/IP network routers to calculate the destinations of messages it is responsible for forwarding. The table is a small in-memory database managed by the router's built-in hardware and software. Each IP address identifies a remote router (or other network gateway) that the local router is configured to recognize. For each IP address, the routing table additionally stores a network mask and other data that specifies the destination IP address ranges that remote device will accept. Home network routers utilize a very small ...view middle of the document...
that classful routing does not support subnet information, and therefore lacking support for VLSM (variable length subnet masks).
Classless Routing if you took a guess that it supports VLSM and different size networks within the same IP address class then you’re catching on Because that is exactly what a classless routing protocol does, so for example we are using a class C address of 192.168.1.0 with a standard subnet mask of 255.255.255.0 or a /24. With a classless routing protocol you can split this network even more instead of having 254 usable hosts in one network; we could have 126 usable hosts with two networks.
The ranges for the first network would start at 192.168.1.1 and end at 192.168.1.126, and the second would start at 192.168.1.129 and end at 192.168.1.254. The subnet mask for both of these networks would be 255.255.255.128. With a classful routing protocol, it would only look at the class of the address in this case a class “C” and not look at the subnet mask and apply a default subnet mask of 255.255.255.0 causing these addresses to be in the same network which in reality they're not.
d. Metric and Administrative Distances- Administrative distance
Administrative distance (AD) is how a router determines which source of routes it should use if it has two identical routes from different sources. In other words, the router needs to be able to determine which routes to trust if it's receiving the same information from two different sources. For a better idea, consider trying to decide which local news program, all of which more or less cover the same events, is most trustworthy.
If you only have one router with one routing protocol and one WAN circuit, or if you're only using static routes, administrative distance doesn't affect your situation. But that doesn't mean you shouldn't be familiar with its purpose.
But if you have a slightly more complex network—say you have two WAN circuits or you're using two routing protocols (even if one of them is static routing) —administrative distance takes on more importance.
The sources of the routes aren't only routing protocols, such as RIP, OSPF, or BGP. Possible sources can also be connected routes (i.e., the interfaces on the router) and static routes (which you entered as network administrator).
The router determines which source is the most trustworthy (i.e., reliable) according to the administrative distance. The lower the administrative distance, the more trustworthy the routing source.
To help make this decision, routers contain a preprogrammed table that lists all of the possible sources and their default administrative distances. Listing A offers an example of what this table looks like. (While administrators can change default administrative distances by using the distance command in Router Configuration Mode, this is usually not advisable.)
2. IPv6 and IPv4:
a. IPv4 address format- IPv4 address has the following format: x . x . x . X where x is called an...