NETACAD 11 IPv4 ADDRESSING Flashcards
Describe the bits in the various sections of an IPv4 address
The bits within the network portion of the address must be identical for all devices that reside in the same network. The bits within the host portion of the address must be unique to identify a specific host within a network.
What is prefix length
he prefix length is the number of bits set to 1 in the subnet mask. It is written in “slash notation”, which is a “/” followed by the number of bits set to 1.
Describe Logical AND
Logical AND is the comparison of two bits. Only a 1 AND 1 produces a 1 and all other combination results in a 0. Any other combination results in a 0.
What addresses exist within each network
network addresses, host addresses, and a broadcast address
Describe IPv4 Unicast, Broadcast, and Multicast
Unicast
Unicast transmission refers to a device sending a message to one other device in one-to-one communications. A unicast packet is a packet with a destination IP address that is a unicast address which is the address of a single recipient.
Broadcast
Broadcast transmission refers to a device sending a message to all the devices on a network in one-to-all communications. A broadcast packet has a destination IP address with all ones (1s) in the host portion, or 32 one (1) bits.
Multicast
Multicast transmission reduces traffic by allowing a host to send a single packet to a selected set of hosts that subscribe to a multicast group. A multicast packet is a packet with a destination IP address that is a multicast address. IPv4 has reserved the 224.0.0.0 to 239.255.255.255 addresses as a multicast range.
Give the types of IPv4 addresses
- Public IPv4 addresses are globally routed between ISP routers. Public IPv4 addresses must be unique, and are globally routed over the internet.
- Not all available IPv4 addresses can be used on the internet. There are blocks of addresses called private addresses that are used by most organizations to assign IPv4 addresses to internal hosts. Most internal networks use private IPv4 addresses for addressing all internal devices (intranet); however, these private addresses are not globally routable.
- Loopback addresses used by a host to direct traffic back to itself.
- Link-local addresses are more commonly known as APIPA addresses, or self-assigned addresses.
Describe how devices broadcast within a network
In an Ethernet LAN, devices broadcast to locate other devices using ARP. Switches propagate broadcasts out all interfaces except the interface on which it was received. Routers do not propagate broadcasts, instead each router interface connects a broadcast domain and broadcasts are only propagated within that specific domain.
What is a large broadcast domain. What are the problems it poses and their solution
A large broadcast domain is a network that connects many hosts. A problem with a large broadcast domain is that these hosts can generate excessive broadcasts and negatively affect the network. The solution is to reduce the size of the network to create smaller broadcast domains in a process called subnetting
What is the advantage of subnetting
Subnetting reduces overall network traffic and improves network performance
In what ways can an administrator subnet?
An administrator may subnet by location, between networks, or by device type.
Describe how subnetting is done
IPv4 subnets are created by using one or more of the host bits as network bits. This is done by extending the subnet mask to borrow some of the bits from the host portion of the address to create additional network bits. The more host bits that are borrowed, the more subnets that can be defined. The more bits that are borrowed to increase the number of subnets also reduces the number of hosts per subnet. Networks are most easily subnetted at the octet boundary of /8, /16, and /24. Subnets can borrow bits from any host bit position to create other masks.
Describe how to Subnet a /16 and a /8 Prefix
In a situation requiring a larger number of subnets, an IPv4 network is required that has more hosts bits available to borrow. To create subnets, you must borrow bits from the host portion of the IPv4 address of the existing internetwork. Starting from the left to the right with the first available host bit, borrow a single bit at a time until you reach the number of bits necessary to create the number of subnets required. When borrowing bits from a /16 address, start borrowing bits in the third octet, going from left to right. The first address is reserved for the network address and the last address is reserved for the broadcast address.
Describe Variable Length Subnet Masking
Traditional subnetting might meet an organization’s needs for its largest LAN and divide the address space into an adequate number of subnets. But it likely also results in significant waste of unused addresses. VLSM allows a network space to be divided into unequal parts. With VLSM, the subnet mask will vary depending on how many bits have been borrowed for a particular subnet (this is the “variable” part of the VLSM). VLSM is just subnetting a subnet. When using VLSM, always begin by satisfying the host requirements of the largest subnet. Continue subnetting until the host requirements of the smallest subnet are satisfied. Subnets always need to be started on an appropriate bit boundary.
What are some considerations an administrator should account for when coming up with an address plan
The address plan includes determining where address conservation is needed (usually within the DMZ), and where there is more flexibility (usually within the intranet). Where address conservation is required the plan should determine how many subnets are needed and how many hosts per subnet. This is usually required for public IPv4 address space within the DMZ. This will most likely include using VLSM.
What specifications should an address plan have
The address plan includes how host addresses will be assigned, which hosts will require static IPv4 addresses, and which hosts can use DHCP for obtaining their addressing information.
