Network Naming
- Understand DNS
- (Notes: DNS & ARP are different protocols! DNS maps friendly names to IP addresses. ARP maps IP addresses to MAC addresses.)
- DNS resolves FQDNs to IP addersses. DNS (Domain Name System!)
- .com & .edu are examples of top-level domains (TLDs).
- www.example.com
- The Individual Host Name is the ‘www.’
- ‘www.’ will take you to a Web domain server.
- ‘ftp.’ will take you to an FTP server.
- ‘mail.’ will take you to a mail server.
- The name of the individual host name can be anything but these are the conventions commonly used.
- Note: ‘ipconfig /all’ –> DNS settings
- Computers & DNS Servers cache address information.
- Apply DNS
- CNAME record creation makes an alias name, or “known name”, often created for user interfacing.
- A reverse lookup zone will resolve an IP address to an FQDN, & are used by mail servers.
- TXT records, (DKMI, and SPF) are used to identify e-mail users and reduce spam.
- Authoritative DNS server
- Lookup zones
- SOA (Start Of Authority) (The 1st entry in a DNS server is a SOA!)
- NS (Name Server)
- “A” record = IPv4; “AAAA” (quadruple A) = IPv6
- Canonical Name or alias (CNAME)
- MX record (Mail Exchange)–special host record for SMTP mail servers.
- Reverse lookup zone.
- PTR (pointer record)
- The Hosts file
- The “hosts” file contains IP addresses & their corresponding names.
- Every computer that runs TCP/IP has a “hosts” file.
- The “hosts” file takes precedence over DNS.
- Net Command
- The ‘Net’ command is a very old command that helps manage a network.
- The ‘net’ command has many different options to manage a network (net use, net share, etc.). (The ‘netuse’ command assigns a drive letter in the local computer to a shared folder in another computer.)
- The ‘net view’ command shows everything that is on the network.
- ‘net accounts’
- ‘net start’
- ‘net stop’
- Window Name Resolution
- “Netbios” is an old protocol that manages the connections based on the names of the computers within a LAN.
- Link Local Multicast Name Resolution (LLMNR) is a protocol that allows hosts to name resolution for hosts on the same local link.
- “nbtstat” is a diagnostic command that can be useful, but has some issues with LLMNR. Nbtstat provides info about the netbios naming service that runs in some Windows-based computers.
- Dynamic DNS
- Dynamic DNS tracks IP address changes of a local device and updates DNS to reflect those changes. The changes are propagated to a DDNS service which sends the changes to the appropriate DNS servers throughout the internet.
- Dynamic DNS enables you to use a DCHP-assigned IP address for connection.
- DDNS providers can update IP information.
- DNS Troubleshooting
- (Note: Use ‘ping’ to check connectivity to a FQDN.)
- Use an IP address of a website to test connectivity without DNS.
- Run ‘ipconfig /flushdns’ to clear the DNS resolver cache, and force a fresh DNS lookup.
- *Run ‘nslookup’ or dig to check the status of a DNS server.
- DIG–(Domain Information Groper)
- Check for misconfiguration.
