DNS and Network Naming Flashcards
DNS
The DNS root
.
DNS ports
UDP 53, sometimes TCP 53
Number of DNS root servers
13; see them at www.root-servers.org
TLD
Top level domain
Original TLD’s
com, org, net, edu, gov, mil, int
Limit on length of DNS name
255 characters, including the periods
Host name
The name for an individual computer
FQDN
Fully qualified domain name
DNS server
A single server running DNS server software
Zone
A container for a single domain that gets filled with records
DNS Record
A line in the zone data that maps a FQDN to an IP address
Zone that lists all hosts on the domain
Authoritative DNS server (aka SOA, Start of Authority)
SOA
Start of authority (zone listing all hosts on the domain); updates the name servers
Name servers
DNS servers subordinate to the SOA but supporting the same domain
Naming rules for name servers
None. Name them what you like (subject to 255 character limit)
HOSTS file
Locally cached file on a PC, overrides DNS
Windows command to verify DNS server info
ipconfig /all
DNS name resolution order
Local cache, local DNS server, root server, TLD server, domain server
Name of UNIX/Linux DNS server tool
BIND
Forward lookup zone
the zone that maps a FQDN to an IP address; the most important part of the DNS server
A records
The IP addresses for all of the hosts on the domain
CNAME records
Stands for “canonical name”. An alias for another host name
MX records
Stands for “mail exchanger.” The IP address of the mail server
AAAA records
The IPv6 addresses of all of the hosts on the domain
Primary zone
Created on the DNS server, act as the SOA for that zone
Secondary zone
Created on other DNS servers, backups to the primary zone
Reverse lookup zone
Maps an IP address to a FQDN. Allows reverse lookup
PTR
Pointer records. In reverse lookup zones. They point to CNAMEs
SMB/CIFS
Server Message Block (nka Common Internet File System). Legacy NetBIOS naming convention. Can run over DNS
Workgroup
A collection of connected local computers running Windows.
Windows domain
A collection of local computers connected to a server running Windows Server. Today Windows domains use DNS names.
Domain controller
Windows Server configured to control a Windows domain
Recommended top level name for Windows domain not on the Internet
.local (but not enforced)
Active directory
An organization of related computers sharing one or more Windows domains. Multiple domain controllers
What happens if primary DNS server goes down
You can use secondary to look up records, but cannot add new records
Active directory-Integrated zone
Allows any Active Directory domain controller to act as a primary zone.
Dynamic DNS
Enables DNS servers to automatically populate the IP addresses in forward lookup zones (usually by polling DHCP servers)
Windows command to force DNS server to update its records
ipconfig /registerdns
DNS SEC
DNS Security Extensions for authorization, authentication, to prevent DNS spoofing
First clue that there is a DNS problem
“Server not found” error
Windows command to flush local DNS cache
ipconfig /flushdns
Using PING to test DNS problems
PING the domain name, then PING an IP address. If only the latter works you have a DNS issue
Windows command to get information about the DNS server, see if it is active
nslookup
Windows command to connect to a DNS server
server [server name or IP] (e.g., server totalhomedc1)
WINS server
Windows Internet Name Service, allows NetBIOS hosts to register their names with just one server rather than broadcast
How to test to see if a connection problem is at the host’s NIC
Ping the loopback (e.g., ping localhost or ping 127.0.0.1)
NetBIOS command to see current cache of NetBIOS names on WINS server
nbtstat -c
NetBIOS command to see other visible local systems
net view
Windows command to see all current connections to a system
netstat (use -s switch to give statistics, can be useful)
Windows command to trace a packet’s route around the internet
tracert
RADIUS ports
UDP ports 1812, 1813
