Network Naming Flashcards
NetBIOS
- used broadcasts for name resolution
- computer broadcasted its mac and name when booted up
- broadcasts made it unacceptable for large networks
- only handled names, SMB handled sharing
NetBIOS ports
TCP ports 137 and 139
UDP ports 137 and 138
SMB
Server Message Block
- shared files and folders over NetBIOS
- TCP port 445
DNS ports
UDP port 53
sometimes TCP 53
DNS root servers
Top level of internet computers
name is a dot .
delegate name resolution to top-level domain servers
TLD
Top level domains
com, org, net, edu, gov, mil, int
who runs TLD
ICANN
Internet Corporation for Assigned Names and Numbers
hostname chars are limited to
letters, numbers and a hypen
is dns case sensative?
no
FQDN
Fully Qualified Domain Name
- complete DNS name
DNS char limit
255
zone
a container for a single domain that gets filled with records
record
a line in the zone data that maps an FQDN to an IP address
authoritative name server
single DNS server on a domain
who registers domain names
ICANN
DNS resolver cache
a memory area that also includes any recently resolved addresses
see current DNS server windows CLI
ipconfig /all
see current DNS server Unix/Linux
cat /etc/resolv.conf
view DNS cache in Windows CLI
ipconfig /displaydns
most popular DNS server in UNIX/Linux
Bind
cache-only dns server
- never authoritative
- only used to talk to other DNS servers to resolve IP addresses
- resolved FQDN’s are cached to speed up future lookups
forward lookup zones
record of IP addresses and FQDNs for computers with a domain
CNAME
canonical name record
- acts like an alias
AAAA Records
equivalent of A records, but for IPv6
MX Records
used exclusively by SMTP servers to determine where to send mail
SRV Record
Generic type of record that supports any type of server
TXT Record
A freeform record that can be used for anything
Two types of Forward Lookup Zones
Primary - created on the DNS server that will act as the primary server
Secondary - created on other DNS servers to act as backups to the primary zone
Reverse lookup zones
enables a system to determine an FQDN by knowing the IP address, called a PTR (pointer) record
SMB ports
With NetBIOS - TCP 137 & 139, UDP 137 & 138
Without NetBIOS - TCP 445
Active Directory
- organization of related computers that share one or more domains
- no single domain controller, all controllers are equal
Active Directory DNS
- all domain controllers are DNS servers
- automatically send DNS info to each other, eliminating zone transfers
Active Directory DNS
- all domain controllers are DNS servers
- automatically send DNS info to each other, eliminating zone transfers
DNS forwarding
forward any DNS request that is not authoritative
DDNS
Dynamic DNS
- enabled DNS servers to get automatic updates of IP addresses of computers in their forward lookup zones by talking to DHCP server
- when DHCP server updates records, it reports it to DNS server
Force DNS server to update its records
ipconfig /registerdns
DNSSEC
DNS Security Extensions
- prevents others from impersonating legitimate DNS servers
- implemented through EDNS (Extension Mechanisims for DNS)
IPAM
IP Address Management
- softwae that includes at minimum a DHCP and DNS server that are specially designed to work together
- Windows Server uses IPAM
Clear DNS cache on windows
ipconfig /flushdns
extra dns query tool on unix/linux
dig (domain information grouper)
Steps to diagnose network troubles
1) Diagnose the NIC
2) Check NIC driver
3) Diagnose Locally - ping other resources on network
4) Check IP and Subnet
5) Run netstat - can show broken applications not connected
6) Run netstat -s
7) Diagnose to the Gateway
8) Diagnose to the Internet
NetBIOS uses what type of namespace?
flat
cant ping loopback
broken nic
what is checked first when trying to resolve an FQDN to an IP address?
host file
