networking again

What is an Ethernet broadcast?

A frame delivered to all hosts in the same Layer 2 segment

What frame type is an ARP request?

A Layer 2 broadcast to FF:FF:FF:FF:FF:FF

What is the purpose of an ARP request?

Discover the MAC address for a known IPv4 address

How does a switch handle a received broadcast?

Floods out all ports except the ingress port

How does a router handle an Ethernet broadcast?

It does not forward it to other interfaces

What is a broadcast domain?

All nodes that receive each other’s Layer 2 broadcasts bounded by a router or VLAN boundary

What message does a DHCP client send first?

DHCP Discover broadcast to locate a DHCP server

Where do Ethernet broadcasts propagate?

Only within the local broadcast domain or VLAN

Each router interface represents what?

A separate Layer 2 broadcast domain

What problem arises in large broadcast domains?

Excess broadcasts consume bandwidth and CPU causing slow performance

How do you reduce broadcast scope in a LAN?

Subnet the network into smaller broadcast domains

What is subnetting?

Using host bits to create additional smaller networks with longer prefixes

What happens when the prefix length increases?

More subnets and fewer hosts per subnet

What is a subnet split?

Dividing a larger network into smaller subnetworks with longer prefixes

What does 172.16.0.0/16 divide into (two /24s)?

172.16.0.0/24 and 172.16.1.0/24

Where do broadcasts go after subnetting?

They remain inside each subnet and do not cross to others

What is required for inter-subnet communication?

Layer 3 routing between the subnets

Fill in the blank: Broadcasts are ______ beyond a router boundary.

not forwarded

Fill in the blank: ARP requests are sent as ______ frames.

broadcast

Fill in the blank: DHCP ______ is the initial client broadcast.

Discover

When should you subnet a flat LAN?

When many hosts generate excessive broadcasts or need policy separation

What security benefit does subnetting provide?

Per-subnet access controls and traffic policies

What fault isolation benefit does subnetting provide?

Fewer devices are affected by misconfigurations or malicious traffic

What must hosts share to communicate directly on one IPv4 LAN?

The same network prefix

What is the directed broadcast for 172.16.4.0/24?

172.16.4.255

What is the limited broadcast address?

255.255.255.255 not routed

How does a switch treat an unknown unicast?

Floods out all ports except ingress until the MAC is learned

Which table lets a switch filter unicasts?

The MAC address table mapping MACs to ports

From which field does a switch learn MAC entries?

Source MAC on incoming frames

Which Ethernet field identifies the upper-layer protocol?

The Type field also called EtherType

Which Ethernet field provides error detection?

The Frame Check Sequence using CRC

What is the purpose of the Start Frame Delimiter?

Marks the start of the frame data after the preamble

What changes when moving from /16 to /24?

Fewer hosts per subnet and more subnets

How is off-subnet traffic forwarded?

Sent to the default gateway for routing