Networking Basics Questions and Answers

Answer: C

Correct answer: ICMP

ICMP carries the error and diagnostic messages of the IP suite, including destination unreachable - of which "network unreachable" is one code - time exceeded, and the echo request and reply that ping uses. A router that has no route to a destination discards the packet and returns an ICMP message to the source. ARP resolves IP addresses to MAC addresses, and TCP handles reliability for its own connections only.

Answer: A

Correct answer: 3 and 4

Trunking is configured with an encapsulation, and there are two: 802.1Q, the IEEE standard, which inserts a four-byte tag into the frame and leaves the native VLAN untagged; and ISL, the older Cisco-proprietary method, which encapsulates the whole frame. VTP is not a trunking protocol - it distributes the VLAN database across a domain and requires trunks to already exist - and "VLAN" is not a protocol at all.

Answer: D

Correct answer: PAT

Port Address Translation, also called NAT overload, maps many inside addresses to a single outside address by giving each conversation a distinct source port number and keeping a translation table of the pairs. It is what allows a whole office to reach the Internet through one public address. Static NAT maps one inside address to one outside address permanently, and dynamic NAT draws from a pool - neither of which lets more hosts out than there are public addresses available.

Answer: D

Correct answer: overlay network

An overlay network is a logical network constructed on top of another, its links being paths through the underlying network rather than physical connections. Peer-to-peer file sharing systems, virtual private networks and content distribution networks are the common examples. It permits new services without any change to the infrastructure, at the cost of routing decisions made in ignorance of the real topology below.

Answer: D

Correct answer: 1 Mbps

A hub is a shared medium: every port is in the same collision domain, and the 10 Mbps is divided among everyone using it. With ten users,

and half duplex means they cannot send and receive at once either. Replacing the hub with a switch would give each host its own collision domain and the full 10 Mbps, which is precisely the difference between the two devices.

Answer: D

Correct answer: all of the mentioned

A node is any device attached to the network that participates in communication, whether it originates the data, forwards it on the way, or receives it as the final destination. The term is deliberately general - hosts, routers and switches are all nodes - and the role a given node plays changes from one message to the next.

Answer: B

Correct answer: Medium

The transmission medium is the physical path along which the signal actually travels - twisted pair, coaxial cable, optical fibre or free space. It is one of the five components of a data communication system, with the message, sender, receiver and protocol. A path or route is the logical sequence of nodes a message passes through, which is a different idea from the physical carrier itself.

Answer: A

Correct answer: NCP

PPP has two sublayers above the physical link. LCP establishes, configures and tests the connection itself, handling authentication, compression, multilink and error detection. NCP then negotiates one control protocol per network layer protocol carried - IPCP for IP, IPXCP for IPX - which is how PPP supports several protocols over one link. HDLC is a different encapsulation altogether, and ISDN is a physical service.

Answer: A

Correct answer: 192.168.168.129-190

The mask 255.255.255.192 is /26, leaving 6 host bits, so the block size is

and the subnets begin at 0, 64, 128 and 192. The address 188 falls in the 128 subnet, whose broadcast is the address before the next subnet, 191. The usable hosts are therefore 129 to 190: 128 is the network address and 191 the broadcast, and neither can be assigned to a host.

Answer: A

Correct answer: personal area network

A PAN covers the space immediately around a person, typically within about ten metres, and Bluetooth is its most familiar technology - connecting a headset, keyboard or fitness tracker to a phone or computer. A LAN spans a building or campus, a WAN a country or the world, and a VPN is a logical network tunnelled over a public one rather than a matter of physical range.