Managing and Troubleshooting Networks Chapter 10 - Network+ Cert

Primary zone

A common type of forward lookup zone. Created on the DNS server that will act as the authoritative name server for that zone.

pointer Record (PTR)

A reverse lookup zone takes a network ID, reverses it, and adds a unique domain called "in-addr-arpa" to create the zone. This is called a pointer Record

cached lookups

a list of Name resolutions that were recently looked up by a DNS server. Each has a specific time to live before they expire, requiring the DNS server to look the address up again. There is also a cache size limit, meaning older lookups could be kicked out if the cache becomes full.

workgroup

a name that organizes a group of computers.

name servers

A Domain will have a single Authoritative name server, and can have many supporting DNS servers that are subordinate to the authoritative name server but support the same domain. Every name name server knows the address of the authoritative name server and each other. The Authoritative name server's job is to make sure that all other name servers are updated for changes.

NetBIOS over TCP/IP

NetBIOS uses ports 137 and 139 for TCP communication and ports 137 and 138 for UDP communication

Cache only DNS Servers

Never the authoritative DNS Server for a domain. Only used to talk to other DNS servers to resolve IP addresses.

A records

Type of DNS entry that are IPv4 addresses and names of systems in a domain. AAAA records are for IPv6

NetBIOS / NetBEUI

Uses broadcasts for name resolution. When a new system boots up into a network it broadcasts its name and MAC address, all over NetBIOS systems document this information. Any time any of these systems is missing NetBIOS information, broadcasting occurs again. Only suitable for small networks as it does not use logical IP addressing. It also causes heavier traffic with these constant broadcasts. NetBIOS was originally intended for sharing folders and printers

Windows Domain

is a group of computers controlled by a computer running windows server. The windows server is configured as a domain controller. All computers within a domain authenticate to the domain controller when they log in.

Authoritative name server

A DNS server that hosts a single zone that lists all the host names on the domain and their corresponding IP addresses.

MX records

A type of entry on a DNS server. Used by SMTP servers to determine where to send mail.

NS records

All of the DNS servers for a domain.

CNAME

Canonical Name A type of entry on a DNS server. Acts like an alias. Allows to refer to a computer on a domain by an alternative name.

Secondary zones

Created on DNS servers to act as backups to the primary zone.

DNSSEC

DNS Security Extensions An Authentication and authorization protocol designed to prevent hackers from impersonating legitimate DNS servers. Implemented through extension mechanisms for DNS (EDNS). Maintains backward compatibility with earlier DNS servers.

DNS terms

DNS Server - A computer running DNS server software Zone - A container for a single domain that gets filled with records records - a line in the zone data that maps a FQDN to a IP address.

DNS

Domain Name System Name resolution protocol

DDNS

Dynamic DNS Created in 1997, Allows a DNS server to et automatic updates of IP addresses of computers in their forward lookup zones, mainly by talking to the local DHCP server.

Reverse lookup zone

Enables a system to determine a FQDN by knowing the IP address.

How to troubleshoot suspected issues with DNS

First flush the DNS, ipconfig /flushdns Then ping any human name address, ping www. microsoft.com If that does not work, but you can ping the IP address of microsoft.com, then you know you have an DNS issue. Verify that you have the right DNS server set. Type nslookup. It should give you the ip address of your DNS server. If you receive server not found, it means your primary DNS server is down or the DNS server IP address is wrong Inside nslookup you can attach and DNS server by typing server <server domain name OR IP address>.

how to force A DNS server to update its records

From command prompt, type ipconfig /registerdns

SMB

Server Message Block Runs on top of NetBT, supports the actual sharing of folders and files. When running on top of NetBT uses ports 137 and 138 for UDP, 137 and 139 for TCP. Today runs independent of NetBT and runs on port 445.

FQDN

Fully qualified Domain Name A complete DNS name, including the host name, and all of its domains. Written out as www.name.com for example. The root domain is on the far right (.com). The middle section (name) is the domain (with any additional domains written to the left of of that domain). The www. portion is the host name.

Top level domain servers

Handles name resolution for domains such as .com, org, edu, gov, mil, and int.

forward lookup zones

IP addresses and FQDNs for computers in a domain are stored here.

Authoritative DNS Server

In charge of knowing the IP addresses for it's server, and is able to provide information of those IP addresses to other DNS servers. Also has a list of other Authoritative DNS servers, and is able to ask other servers for an IP address it does not know. IF a Authoritative DNS server goes down, secondary DNS servers can take over, however no updates can be made until the primary DNS server goes back up and is updated itself.

NetBIOS over TCP/IP (NetBT)

Runs NetBIOS on top of TCP/IP.

SOA

Start of Authority Every forward lookup zone requires a SOA record. This defines the single DNS server in charge of the forward lookup zone.

DNS root servers

The top dog DNS server is actually a bunch of powerful computers dispersed around the world. Has the complete definitive name resolution table bu t most name resolution work is delegated to other DNS servers DNS uses port 53

Active Directory

an organization of related computers that share one or more Windows domains. No single domain controller is in charge, all are equal, so if one goes down another can take over for it.

hosts file

contained a list of IP addresses for every computer on the internet in the early days. Corresponded IP address with computer names. Today the file is rarely used at all although it still exists in both Windows and Linux systems. Even today however the OS will always look in the Hosts file first when attempting name resolution before moving on to DNS.

DIG

domain information groper Unix,Linux tool, similar to nslookup but runs non interactively. Provides a large amount of information.

hierarchical name space

permits greater flexibility y enabling admins to give networked systems longer, more fully descriptive names.

name resolution

the process of converting a human named address to the real IP address

nslookup

tool used from command prompt, enables DNS server queries.