DNS Resolution

This page is meant to help with DNS issues such as determining if DNS is being handled properly.

Caching and Time To Live (TTL)
DNS records are cached. How often records that have been cached are updated depends on their Time To Live (TTL) values. $ nslookup -debug example.com ns1.dreamhost.com Server: ns1.dreamhost.com Address: 66.33.206.206#53 Got answer: HEADER: opcode = QUERY, id = 17, rcode = NOERROR header flags: response, auth. answer, want recursion questions = 1, answers = 1,  authority records = 0,  additional = 0 QUESTIONS: example.com, type = A, class = IN    ANSWERS: -> example.com internet address = 208.113.209.221 ttl = 14400 (4 hours) Name:   example.com Address: 208.113.209.221

This is an example of a domain hosted with DreamHost. The TTL is set to 4 hours. If an ISP honors this TTL value then if the IP address above changed one should expect the ISP to return the new address in 4 hours or less.

When the nameservers are changed for a domain it may take much longer for an ISP to resolve to the new IP address because the TTL may be set to 2 days. This is why you may hear it takes two days to "propagate."

Troubleshooting
For domains and subdomains hosted at DreamHost, the records should appear in the "DNS" panel when using the Domains -> Manage Domains section of the DreamHost Web Panel.

Next they should be returned when querying the DreamHost nameservers directly. $ nslookup -debug -norecurse -query=A example.com ns1.dreamhost.com Server:        ns1.dreamhost.com Address:       66.33.206.206#53 QUESTIONS: example.com, type = A, class = IN    ANSWERS: -> example.com internet address = 208.113.209.221 AUTHORITY RECORDS: ADDITIONAL RECORDS: Name:  example.com Address: 208.113.209.221

DNS is configured correctly given that the "A" record in our "DNS" panel shows the same IP address.

Now here is an example of a domain not hosted at DreamHost: Server:        ns1.dreamhost.com Address:       66.33.206.206#53 QUESTIONS: example.com, type = A, class = IN    ANSWERS: AUTHORITY RECORDS: ADDITIONAL RECORDS: ** server can't find example.com: SERVFAIL

So at this point if you had used Domans -> Manage Domains to add the domain and waited a while you should try to refresh the DNS information using the "DNS" panel. If that doesn't work contact Support.

Now so far we've queried DreamHost directly. But your local computer may be configured to use a local computer for DNS resolution. In addition an ISP will provide IP addresses for your computer to connect to for DNS resolution. DreamHost support won't be able to help if a DNS problem lies with either one, or any DNS servers between DreamHost and the one you use for DNS resolution.