A list of protocols used by a system, one protocol per layer, is called ________
Answer: B
Explanation: A protocol stack refers to a group of protocols that are running concurrently that are employed for the implementation of network protocol suite. Each layer in the network model has to use one specific protocol from the protocol stack.
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How long is an IPv6 address?
Answer: D
Correct answer: 128 bits
An IPv6 address is 128 bits, four times the 32 bits of IPv4, and is written as eight groups of four hexadecimal digits separated by colons - for example 2001:0db8:0000:0000:0000:ff00:0042:8329, which may be shortened to 2001:db8::ff00:42:8329. The enlarged space gives about \( 3.4 \times 10^{38} \) addresses, enough that address exhaustion ceases to be a design constraint. Note the unit: 128 bits, which is 16 bytes, not 128 bytes.
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Which WLAN IEEE specification allows up to 54Mbps at 2.4GHz?
Answer: C
Correct answer: G
802.11g runs in the 2.4 GHz band at up to 54 Mbps and is backward compatible with 802.11b, which is why it displaced it so quickly. 802.11a also reaches 54 Mbps but does so at 5 GHz, so it is not compatible with b or g equipment. 802.11b is limited to 11 Mbps, and 802.11n is faster than 54 Mbps and works in both bands.
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A list of protocols used by a system, one protocol per layer, is called:
Answer: B
Correct answer: protocol stack
A protocol stack is the particular set of protocols a system actually runs, one at each layer - for example Ethernet, IP, TCP and HTTP. A protocol suite is the wider family from which they are drawn, such as TCP/IP as a whole, and protocol architecture refers to the layered design itself. The stack is the concrete implementation; the suite and the architecture are the collection and the pattern.
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What PPP protocol provides dynamic addressing, authentication, and multilink?
Answer: C
Correct answer: LCP
The Link Control Protocol negotiates the characteristics of the PPP link itself: authentication with PAP or CHAP, dynamic addressing, callback, compression, error detection and multilink. NCP is the layer above it, negotiating one control protocol for each network layer protocol carried. The division is worth holding: LCP concerns the link, NCP concerns what is carried over it.
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Which command is used to upgrade an IOS on a Cisco router?
Answer: D
Correct answer: copy tftp flash
An upgrade writes a new IOS image from a TFTP server into flash, so the source is tftp and the destination flash. Reversing the two words gives copy flash tftp, which is the backup. copy tftp run and copy tftp start load configuration files rather than images, and config net merges a configuration from the network into the running one.
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A _______ is the physical path over which a message travels.
Answer: B
Correct answer: Medium
The transmission medium is the physical path a signal travels along - twisted pair, coaxial cable, optical fibre, or the free space used by radio. It is one of the five components of a data communication system, alongside the message, the sender, the receiver and the protocol. A route or path is the sequence of devices a message passes through, which is a logical rather than a physical notion.
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Which protocol is used to send a destination network unknown message back to originating hosts?
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.
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What protocols are used to configure trunking on a switch?
1.VLAN Trunking Protocol
2.VLAN
3.802.1Q
4.ISL
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.
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What flavor of Network Address Translation can be used to have one IP address allow many users to connect to the global Internet?
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.
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