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udemy-aws-certified-solutions-architect-associate/DNS101.md

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+### What is DNS?
+- You know DNS, right?
+
+### Ipv4 vs IPv6
+- bits: 32 vs 128
+- addresses: 4,294,967,296 vs 340,282,366,920,938,463,463,374,607,431,768,211,456
+
+### Top Level Domains
+http://www.iana.org/domains/root/db
+
+### Domain Registrars
+- GoDaddy.com, 123-reg.co.uk
+
+### SOA Records
+### NS Records
+### A Records
+### TTL
+### CNAMES
+### Alias Records
+- Work like a CNAME record, but can't be used for naked domain names (zone apex)
+
+### Examp Tips
+- ELB's do not have pre-defined IPv4 addresses, you resolve to them using a DNS name
+- Understand the difference between an Alias Record (which is Not get charged) and a CNAME.
+- Given the choice, always choose an Alias Record over a CNAME.