CISCO Exam 3

What is the difference between an IP address and a MAC address?

An IP address is a logical address used to identify a device on a network. A MAC address is a physical address assigned to a network interface.

At what OSI layer does a router operate?

Layer 3, the Network layer.

What are the four basic processes of the Network layer?

Addressing, encapsulation, routing, and decapsulation.

What is routing?

The process of selecting a path for packets to reach their destination.

What is a hop?

One step a packet takes from one router to another.

What Network layer protocol routes data over the Internet?

Internet Protocol (IP).

What are the three main characteristics of IP?

Connectionless, best-effort delivery, and media independent.

What does connectionless mean?

IP does not establish a connection before sending packets.

What does best-effort delivery mean?

IP tries to deliver packets but does not guarantee delivery.

What does media independent mean?

IP can operate over different types of network media.

When sending data from Cal U to Google, how many times does a packet's contents change?

The IP payload normally stays the same as routers forward it, although headers change. If the question means the payload specifically, it does not normally change.

What does the IP version field identify?

Whether the packet uses IPv4 or IPv6.

What does Time to Live (TTL) do?

It decreases at each router to prevent packets from circulating forever.

What does an IP address identify?

A device's logical address on a network.

What are the limitations of IPv4?

It uses 32-bit addresses, has a limited address supply, and often requires NAT.

What are the advantages of IPv6 over IPv4?

A much larger address space, a simplified base header, no broadcast, and improved support for auto-configuration.

Which packet header is bigger, IPv4 or IPv6?

IPv6 has a larger base header: 40 bytes compared with IPv4's minimum of 20 bytes.

How does a host determine if a destination is local or remote?

It compares the destination IP address with its own network using its subnet mask or prefix.

What does a host's routing table contain?

Routes to directly connected networks, remote networks, and possibly a default route.

What is a directly connected route?

A route to a network directly attached to a router's interface.

What is a remote route?

A route to a network that must be reached through another router.

What is the difference between static and dynamic routing?

Static routes are manually configured. Dynamic routes are learned and updated using routing protocols.

What is a default gateway?

The router interface a host uses to send traffic to other networks.

What devices can act as a default gateway?

A router or a Layer 3 switch.

What happens if a device has no default gateway configured?

It can communicate with local devices but generally cannot reach remote networks.

What happens if an incorrect default gateway is configured?

The device may be unable to communicate with remote networks.

What is ARP?

Address Resolution Protocol, which finds the MAC address associated with an IPv4 address on a local network.

How does ARP work?

A device broadcasts an ARP request, and the device with the matching IPv4 address replies with its MAC address.

What are the basic functions of ARP?

Resolving IPv4 addresses to MAC addresses and storing those mappings in an ARP table

Does IPv6 use ARP?

No. IPv6 uses Neighbor Discovery Protocol (NDP).

What is stored in an ARP table?

Mappings between IPv4 addresses and MAC addresses.

How can an ARP table be populated?

Dynamically through ARP requests and replies, or manually using static entries.

Are ARP table entries permanent?

Dynamic entries expire after a period of time. Static entries remain until removed or changed.

Where is the ARP table stored?

In the device's memory.

What destination MAC address is used when communicating with a local device?

The MAC address of the destination device.

What destination MAC address is used when communicating with a remote device?

The MAC address of the default gateway.

What are two possible problems with ARP?

ARP broadcasts create extra network traffic, and ARP spoofing can be used to redirect traffic maliciously.

What happens if no device responds to an ARP request?

The sender retries the request. If resolution fails, the packet cannot be sent to that destination at Layer 2.

What does IPv6 Neighbor Discovery Protocol provide?

Address resolution, router discovery, neighbor reachability checks, and other local-link functions.

How does address resolution work in IPv6?

NDP uses ICMPv6 Neighbor Solicitation and Neighbor Advertisement messages to discover MAC addresses.

When a router is running, where are startup-config and running-config stored?

Startup-config is stored in NVRAM. Running-config is stored in RAM.

What is the difference between startup-config and running-config?

Startup-config is loaded when the router starts. Running-config contains the current configuration

What types of passwords can be configured on a router?

Console passwords, VTY passwords, enable passwords, and enable secret passwords.

Why might a banner message be configured?

To display a warning or notification to users accessing the device.

Why is the login command used?

It requires users to enter a password on a line where password authentication is configured.

Are Cisco router commands case-sensitive?

Yes, commands and their arguments can be case-sensitive.

How do you save the running configuration?

Use copy running-config startup-config

How do you encrypt unencrypted passwords in a Cisco configuration?

Use service password-encryption in global configuration mode.

Where can you see password encryption in the configuration?

In the output of show running-config, where supported passwords appear in encrypted or hashed form.

How do you display the routing table?

Use show ip route .

What should you do before saving the running configuration?

Verify that the configuration is correct and working.

What does the shutdown command do?

Administratively disables an interface.

What does the no shutdown command do?

Administratively enables an interface.

Why configure a description on a router interface?

To identify the interface's purpose or connection. It appears in the interface configuration and can be viewed with show commands.

Does a switch need an IP address?

A Layer 2 switch does not need an IP address to forward frames, but it needs one for remote management.

Does a switch need a default gateway?

A Layer 2 switch needs one for management traffic to reach remote networks, but not for ordinary local switching.

On which switch interface is an IP address configured?

On a switched virtual interface (SVI), such as interface vlan 1, rather than on a regular physical Layer 2 port.

When does data travel through a router?

When the destination is on a different IP network.

When does data not need to travel through a router?

When the source and destination are on the same IP subnet and can communicate directly

Why configure a default gateway on a switch?

To allow the switch to send management traffic to devices on remote networks.

How do you identify the default gateway in a network diagram?

Find the router or Layer 3 switch interface connected to the device's local subnet.

How do you identify the default gateway's interface name and number?

Locate the interface connected to the local network in the diagram and read its label, such as GigabitEthernet0/0.