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Appendix 3

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verickle's version from 2016-11-01 20:03

Network Infrastructure Device Characteristics

DeviceNumber of Collision Domains PossibleNumber of Broadcast Domains PossibleOSI Layer of Operation
Hub111
Bridge1 per port12
Switch1 per port1 per port2
Multilayer switch1 per port1 per port3+
Router1 per port1 per port3+
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Common DNS Record Types

Question Answer
AAn address record (that is, A record) maps a hostname to an IPv4 address.
AAAAAn IPv6 address record (that is, AAAA record) maps a hostname to an IPv6 address.
CNAMEA canonical name record (that is, CNAME record) is an alias of an existing record, thus allowing multiple DNS records to map to the same IP address.
MXA mail exchange record (that is, MX record) maps a domain name to an e-mail (or message transfer agent) server for that domain.
PTRA pointer record (that is, PTR record) points to a canonical name. A PTR record is commonly used when performing a reverse DNS lookup, which is a process used to determine what domain name is associated with a known IP address.
SOAA start of authority record (that is, SOA record) provides authoritative information about a DNS zone, such as e-mail contact information for the zone's administrator, the zone's primary name server, and various refresh timers.
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