Does my ISP cache the DNS?

Solution 1:

Yes. Your ISP is almost certainly caching DNS settings for some period of time. They are supposed to refresh the records when the TTL expires. Unfortunately there are a large number of ISPs that seem to ignore TTLs all together in their DNS caching schemes. If you happen to be on one of those ISPs it could be hours or even days before they respect the new records, even if you have a very low TTL set.

Solution 2:

I faced the same issue and fixed it via using google DNS

Open your Network /IP settings Use DNS servers as:

8.8.8.8
8.8.4.4

These are google DNS and will solve your prob until ur ISP refresh the catche

Solution 3:

There are two things here. One is the time it takes for your domain registrar to place the DNS entries you've provided through some sort of web form / management panel on the registrars DNS servers. This 'update' process usually occurs within 15 minutes.

Two there is the TTL field of each RR (Registry Record), which basically says: if someone asked about domain.com before, cache the domain.com -> IP address RR for TTL seconds (cache so I don't have to ask an authoritative server again / every time some host asks about domain.com). TTL values vary, usually they are set to about 1 day == 86400 seconds.

You can actually check if the DNS server of your ISP cached the result, by asking the ISP DNS server explicitly, using the commands:

nslookup domain.com ns1.isp.com
dig domain.com @ns1.isp.com

The TTL in the response field will indicate for how much time the RR is cached on the server.