CCENT Concepts Pt. 4

Question 1

Virtual Circuit

Answer 1

In packet-switched services like Frame Relay, VC refers to the ability of the
two DTE devices (typically routers) to send and receive data directly to each
other, which supplies the same function as a physical leased line (leased
circuit), but doing so without a physical circuit. This term is meant as a
contrast with a leased line or leased circuit.

Question 2

Rules of IP addresses needing to

be in the same grouping.

Answer 2

All IP addresses in the same group
must not be separated by a router. IP
addresses separated by a router must
be in different groups.

Question 3

Size of A Network

Answer 3

1 Byte of Network Bytes
3 Bytes of Host Bytes
2^24 -2 of Addresses per network

Question 4

Size of B Network

Answer 4

2 Bytes of Network Bytes
2 Bytes of Host Bytes
2^16 -2 of Addresses per network

Question 5

Size of C Network

Answer 5

3 Bytes of Network Bytes
1 Byte of Host Bytes
2^24 - 2 of Addresses per network

Question 6

Class A - Valid Network Range

Answer 6

1 to 126
1.0.0.0 to 126.0.0.0
126 Possible Networks
16,777,214 Possible Hosts

Question 7

Class B - Valid Network Range

Answer 7

128 to 191
128.0.0.0 to 191.255.0.0
16,384 Possible Networks
65,534 Possible Hosts

Question 8

Class C - Valid Network Range

Answer 8

192 to 223
192.0.0.0 - 223.255.255.0
2,097,152 Possible Networks
254 Possible Hosts

Question 9

Simple Routing Logic

Answer 9

If the destination IP address is in the same subnet as I am, send the packet
directly to that destination host.
If the destination IP address is not in the same subnet as I am, send the
packet to my default gateway (a router’s Ethernet interface on the subnet)

Question 10

Router Forwarding Decisions and

the IP Routing Table

Answer 10

Step 1 - Use the data - link FCS field to ensure that the frame had no errors; if
errors occurred, discard the frame.
Step 2 - Assuming the frame was not discarded at step 1, discard the old datalink
header and trailer, leaving the IP packet.
Step 3 - Compare the IP packet’s destination IP address to the routing table,
and find the route that matches the destination address. This route identifies
the outgoing interface of the router, and possibly the next-hop router.
Step 4 - Encapsulate the IP packet inside a new data-link header and trailer,

Question 11

ARP

Answer 11

Address Resolution Protocol. An
Internet protocol used to map an IP
address to a MAC address.

Question 12

Default gateway/ default router

Answer 12

On an IP host, the IP address of some router to
which the host sends packets when the packet’s
destination address is on a subnet other than the
local subnet.

Question 13

DHCP

Answer 13

Dynamic Host Configuration Protocol. A protocol
used by hosts to dynamically discover and lease an
IP address, and learn the correct subnet mask,
default gateway, and DNS server IP addresses.

Question 14

DNS

Answer 14

Domain Name System. An application
layer protocol used throughout the
Internet for translating hostnames into
their associated IP addresses.

Question 15

Host Part

Answer 15

A term used to describe a part of an IPv4 address
that is used to uniquely identify a host inside a
subnet. The host part is identified by the bits of
value 0 in the subnet mask.

Question 16

IP address

Answer 16

Internet Protocol. The network layer
protocol in the TCP/IP stack, providing
routing and logical addressing
standards and services.

Question 17

logical address

Answer 17

A generic reference to addresses as defined by Layer 3 protocols, which do
not have to be concerned with the physical details of the underlying physical
media. Used mainly to contrast these addresses with data-link addresses,
which are generically considered to be physical addresses because they differ
based on the type of physical medium.

Question 18

network broadcast address

Answer 18

In IPv4, a special address in each classful network that can be used to
broadcast a packet to all hosts in that same classful network. Numerically, the
address has the same value as the network number in the network part of the
address, and all 255s in the host octets - for example, 10.255.255.255 is the
network broadcast address for classful network.

Question 19

network number/network address

Answer 19

A number that used dotted decimal
notation like IP addresses, but the
number itself represents all hosts in a
single Class A, B, or C network

Question 20

network part

Answer 20

The portion of an IPv4 address that is
either 1,2, or 3 octects/bytes long,
based on whether the address is in a
Class A, B, or C network.

Question 21

routing table

Answer 21

A list of routes in a router, with each route listing the destination subnet and
mask, the router interface out which to forward packets destined to that
subnet, and, as needed, the next-hop router’s IP address.

Question 22

subnet broadcast address

Answer 22

A special address in each subnet specifically the
largest numeric address in the subnet, designed so
that packets sent to this address should be
delivered to all hosts in that subnet.

Question 23

subnet number/subnet address

Answer 23

In IPv4, a dotted decimal number that represents all addresses in a single
subnet. Numerically, the smallest value in the range of numbers in a subnet,
reserved so that it cannot be used as a unicast IP address by a host.

Question 24

subnet part

Answer 24

In a subnetted IPv4 address, interpreted with classful addressing rules, one of
three parts of the structure of an IP address, with the subnet part uniquely
identifying different subnets of a classful IP network.